It took me several years before I sought help in therapy (in the beginning I sought help because of deep depression and chronic anxiety; couldn't sleep, relax, etc.) and during that process was diagnosed with PTSD. I can only speak to my experience, but in reading through numerous threads since I joined this forum a couple of weeks ago, I see many have the same symptoms I do, and these are similar to what you're describing.
First thing is knowing what you're feeling/experiencing is a normal mental/emotional response to abnormal stress, aka trauma.
So, for me, discovering the fact I wasn't going crazy but only reacting to traumatic events from my past helped me get started on the path to feeling whole, as you mentioned desiring. After I read several books and became familiar with the symptoms associated with PTSD, and in conjunction with therapy, I was able to begin the dismantling process of all I had internalized during and after violent encounters (I was in law enforcement: SWAT and EOD for years).
The startle factor you mentioned resulting from sudden, loud noises, is common also. I still have it at times, especially when stressed.
The majority of the therapy I've been through has been focused on normalizing the feelings, giving vent, expression, etc., and releasing the toxic effects of the suppressed mental/emotional wounds from traumatic events. And, the wounds are real, trust me. For some it only takes one such event, and if numerous traumatic events accumulate, suppressed within us, the effects can be devastating.
Be easy on yourself during any process of healing. It takes time, but is worth all that's involved in becoming whole once more.
