Hey Dubby
I know that sometimes some pills will cause weight gain. There isn't much to do about it if that's the case, I'm afraid. Exercise is good if you can do that. It helps with the depression and anxiety as well.
Sometimes the more meds you're on the more difficult it is to navigate through PTSD. I'd ask the doctor about the meds you're on. Sometimes they'll prescribe one for depression, one for anxiety and one for some other psych condition when there is a one med that will treat them all. Less is better if you can go that route.
I know you're new and I don't know you yet but I'll give you some of the things I do that seem to help me. I try to eat a good diet; balanced meals, fruits and vegs, keep the beef low get protein from fish and chicken. Try not to drink more than one drink a day if at all. Find an exercise routine that you like and will stick with. Even just taking a walk can make you feel better. Gets your blood circulating. If you're in therapy, stick with it. If you're not start. It can make the biggest impact on getting better. You actually can get better. No cure, but better which is good.
Try not to worry or put guilt on yourself for what you aren't doing yet. Just take it a day at a time. As they say, how do you eat an elephant; one bite at a time. Hope this is a help and if I've been remiss; Welcome to the forums.
JarHed