My husband has issues with PTSD and, while he is not a health care professional, he is a chaplain. When he first got home from Iraq, he wasn't sure if he would ever be able emotionally and spiritually to return to pastoral ministry. After several months of time away from the pulpit, he took a position as an interim minister and is now serving two rural churches, although he does have a disability rating.
The biggest challenges that you might face are flashbacks should you deal with trauma patients. My husband has had flashbacks to times when soldiers died and, although they are very infrequent now, his memories are still triggered when we watch certain medical shows. He once had a flashback while watching M*A*S*H
You sound like a very caring, compassionate person who has a lot to offer the nursing profession. It can take a while to get into a nursing program because of prerequisites and wait lists, so you might want to take a CNA course, which is usually affordable and of short duration, so that you can work as a CNA to see if you do enjoy the work and learn if there are particular stimuli that trigger your PTSD. If you discover that the stress level is more than you wish to take on or that it causes flashbacks and such, then you have an answer and can look into other ways to help people, maybe other health care career opportunities. But if you are okay with the stress and don't have many triggering events, you may find you're in exactly the right place!
I would strongly suggest speaking with your local VA representative about the new GI bill, which I believe is more generous in its educational benefits, and about support groups, if you feel the need for one, for your PTSD. My husband found a lot of support from his colleagues as several of his chaplain buddies were deployed at about the same time. Many of them had similar experiences when they returned home, particularly wondering if they, too, could be effective in civilian life while dealing with PTSD.
BTW, a word of warning though: you may wish to keep the PTSD to yourself while you're in a nursing program or at work. I wish nurses were more understanding of each other, but there's still a stigma associated with needing help and some nurses seem to lack compassion when it comes to their peers. There's unfortunately this notion of nurses with problems being somehow "damaged goods" and people who are on antidepressants or have received treatment may face discrimination or at least bear the brunt of staff gossip. It isn't right but it is reality.
I think you can do this!
If I can be of any help, please LMK. You will also find excellent support people all around AN, many people who are very willing to help. I wish you the best!!!