Good Morning and Bless your heart.
I want to welcome you and tell you that not all goes unnoticed by your family, whom suffers from PTSD. So, please don't feel like you are not having an impact, that is positive.
I will share with you something that has often came up in my struggles with PTSD, and maybe somewhere there may be some glimmer of light that will help you and your family out.
Boundaries, are often clouded by sufferers of PTSD; I can say that all too often those closest to us, whom are sufferers/Survivors of MUltiple life trauma events, get the brunt of the violations of boundaries. Maybe it's because of our lashing out, and the guilt that is felt by those whom love us, that we are given too much latitude; which later becomes problematic.
All of the materials and counseling in the world does not replace sound boundaries with PTSD sufferers; as I found out in a not too subtle approach on the subject, by my therapist. Often times, I found that I had not sound idea of boundaries and often just rampaged over the borders of personal boundaries. MY therapist suggested a book called Boundaries. IT was a kick in the teeth and stomach to me and and my family; as it forced us all to recognize that everyone has boundaries which have to have consequences, and violation of those are not accepted.
Enforcement is never comfortable, but the book gives sound advice (in my opinion), to establish a mutual respect between everyone. IT works on a religious base, without beating or preaching religion. It is a glimpse which allows for everyone to work on personal roles and consequences, which are soundly based and backed in God's word and teachings. Yet, it is presented in a non-denominational none confrontational manner.
Both the sufferers and the family/friends who support us, have equal roles which are not easy to live with. I know that there are times that I have no idea what I need, what I want, and who I want and need it from. So, in this I tend to lash out, act out, alienate, self pitty, and the last thing I have on my mind is that others want to help; but I have no idea what I need. Unfortunately, those who try to help, feel like they can not do anything right.
Just know, you are doing everything right! You are doing all that you can! Get the book and draw some mutually respectable means of boundaries; even if it feels totally uncomfortable for everyone involved.. just because we were dealt a shitty hand, does not give us who suffer from PTSD to trample on other's boundaries and self esteem. I learned that the hard way. And yes, it was through that book I was led to understand this.
Again, you are not to blame for the trauma that your family members endured! Don't take the role as the punching bag, for their frustration; It's not your job and is not healthy for anyone!
Bless your heart! Just know that you can not give things, or support to people who have no idea what they need! In the same light, you have to take care of your own mental health needs.