Dear Not Important (great act of Humility there-Kudos!)
I so very very much Understand where you are coming from and still feel that way myself about being "Under Diagnosed".
I think for myself it's about Validating the Constant Horrors I am put through, that get worse by the Day?
Ironically now I suffer from the EXTREME Opposite of that out of Retaliation! This is Not Good!
As far as the "Under Diagnosis" aspect goes it's actually far better to have less Diagnoses than very Stigmatic Ones. What goes into your "Medical record Set" and yes your "Mental Health records are apart of your Medical records, is Permanent and Cannot be Removed even by a Court Order! This can be Devastating and cause very serious Life Threatening Situations as well as Serious PTSD all by it's self!
That said though, I still am struggling to get an Accurate Assessment done that is Valid and will erase (Over ride actually) the Horrific Retaliatory "Diagnoses that were all dumped into my Permanent Medical Records last month in a matter of seeing a "Psychiatrist" who believes that the DSM is for Research Purposes Only and I have never met before in my life. You DON'T Want This!!!
Just a suggestion from all that I have been through for exactly the very same reasons as you, is this...
"Humbly" just as you can and quietly, search out an Ethical and Competent Clinician (that may take a long time and may have to travel many many miles to see), and have a Thorough Mental Health Assessment with the understanding that whatever comes up is NOT to be added to your Medical Record Set!
The reason I say this is because something like "PTSD" is viewed by most (professionals included) as "Dangerous" and can and will be used against you out of Fear and Ignorance. Trust me, I am living proof of that and even "Childhood Abuse" on your Record can and will be used to hurt you! The less you have actually in your medical Records for Idiots to see the safer you are from them.
Now back to the Reason why we actually need an Accurate Diagnosis (even if it's not in our files) is so that we can start to get Effective Treatment for our conditions. I would suggest IF you can find a Qualified and Ethical "Professional" (Which is Far Rarer than one may expect), I would ask to have the Assessment Results "Diagnoses" put on a Document that Validates these that you can prove that it was done, but Demand that they do not go into your Records.
An Ethical Clinician is well trained to do just that and they should always discuss what I just said for those very Reasons! It's apart of their Code of Ethics and is "Do No Harm". That is a tell tale sign if you find one that understands and agrees that they are a cut above the trash that are given Licenses to "Practice".
Now with this Legal Document of your Accurate Conditions (Diagnoses) you can start to find a suitable Therapist who is worth their salt. They are very few and far between and often are all booked up and don't take Medicare/Medicaid.
As you well already know, even your Diagnosis of "Asperger's syndrome" (which no longer exists in the Current DSM-5) is so often Misunderstood and is often seen as a negative term for behaviors. It's now been absorbed into the "Autism Spectrum" which is actually an improvement as far as how you will be treated by "Professionals" who don't even comprehend what that even is.
From just what little bit I read in your post here, it's even possible that your "Asperger's syndrome" may be a Mis-Diagnosis and is actually a "Dissociative Disorder instead. If you have had anything like a childhood like most of us here, you certainly meet the Criteria. PTSD is a "Dissociative Disorder". Dissociation is not a symptom of PTSD but rather the other way around! They have known this for well over 125 years. PTSD is what is called "level I Trauma" or "Simple PTSD" because it's a low level form of Trauma. If a person gets "PTSD" as a child (or juvenile) it by default becomes what is called "Level II Trauma" or "Complex PTSD", which is now finally in the ICD-11 slated for final release in a year.
As anyone here can tell you, this "Simple PTSD" is pure hell and is often more than a Human being can deal with, (My self included!) so I am in no way being dismissive or Trivializing Simple PTSD!
However Level II or III Trauma is a whole world unto it's self and has so many additional features and symptoms because it has shaped our nervous systems and brains since the critical developmental stages of early childhood! It's far far more involved to Diagnose (currently) and also effectively Treat than the simpler form of single incident PTSD (such as a car accident as an adult).
Level III Trauma is the very worst a Human being can have due to the very extreme severity of Trauma that was Experienced at a Very Young Age (ages 2-9 years old) and is Far more common than is Realized by "Professionals". Level III Trauma IS and Only what is called "Dissociative Identity Disorder" formally called "Multiple Personality Disorder" or even earlier in the Victorian era as "Split Personality Disorder". A Human Being cannot typically get it after the age of 9 years old due to Neurological Childhood Development stages. Statistically in the DSM, it's more common than Bi Polar or Schizophrenia and due to Ignorance is almost always Misdiagnosed as some other disorders. It takes 7 years for the average sufferer of Level III Trauma to be accurately Diagnosed!
Mental Health aka "Psychology" in Universities completely Ignore and don't teach about Trauma in Schools. The Entire Category of Trauma aka "Dissociation" is unheard of in ANY University due to Freud's Famous Recanting of his best work and has been buried ever since, until the last 35 years.
It's quite possible that many of the symptoms of "Asperger's syndrome" are actually "Complex Trauma" instead of Autism. I know very little about "Autism" so please forgive any ignorance on m part on that subject, but I do know that even "Complex PTSD" and "Dissociative Identity Disorder" are Very Treatable and can be Healed in less than a Decade in the worst cases. But Usually take 2 to 5 years tops. The Official Treatment for them are the same and are very Intensive Trauma Therapies. That is a wonderful thing compared to "Schizophrenia" or "Bi Polar" which are a Diagnosis for Life. :)
I know this is a lot to absorb and many here who are not informed will attack me for carrying the message of International Experts in the Field of Trauma, such as Dr Bessel Van der kolk, Dr Onno Van der Hart, and the others. But regardless the message here is that I totally agree with getting a complete and Accurate Diagnosis! If we receive "Under Diagnoses" or "Mis-Diagnoses" , the "Treatment" for them is "Mis-Treatment" which is actually far worse than none at all!
But I can't stress this enough either...Keep as much of these "Diagnoses" OUT of Your Medical records" as Humanly Possible at All Times! Once they are Entered (often without your knowledge or permission) they are there for Life AND WILL Be used against you by Unethical and Dangerous "Professionals"!
I study Neurology, Biology of the Nervous system, Psychology etc extensively for I have to due to my Trauma that is ongoing. The Scientific and current state of the art conclusions is Exactly what you already stated and is quite simple when it comes to Healing us of Trauma. You stated it very precisely and clear and wish to Point it out...
"I come to this forum hoping I can find solidarity with some people and communicate with compassion, reason, and understanding - three things that I do not receive in real life."
If a Human being has enough of this sort of Unconditional Love, The International Trauma Experts all agree that it IS the Cure and as Human Beings is Required to to be Healthy. :)
As you clearly stated those three things are not something you have in your life and is Very Traumatic as a Direct Result. Reverse these conditions and we will all be saying "PTS what?" <3
Much Love and Empathy *hugs*
Mark