First of all, you have accomplished and contributed quite a lot. Be proud of what you've done: military, medic, college, etc. There are plenty of people out there who choose not to accomplish or contribute anything in their entire lifetime.
It's good to see that you've found a mentor at school. So far, it looks like you're off to a great start.
If I were to make a suggestion, I would tell you to utilize any mental health professional available to you whether that be at school or through your military benefits. There's nothing wrong with seeking help. Plenty of people of all ages, backgrounds, professions do. Sometimes, it's good to even simply talk about your experiences as you are doing here. Life affects us all.
You say you failed the NREMT twice. Well, it's simply a test, and a bad one at that. Before moving a year ago, I taught EMTs and paramedics. I can tell you that many do not pass everything the first time.
As for that PA, there are people like that everywhere in medicine. But, how are you suppose to know how to do something if you've never been shown? I didn't know how to check a blood glucose or perform injections until I was taught. Shame on him or her for berating you for being safe and honest.
I think you're expecting too much of yourself right now. Try to take everything a day at a time, a semester at a time. Ask your mentor if he or she or someone else can help you plan out your future. Then, have someone else look over your plan.
You've worked hard to get to where you are now. Keep it up, man.
Good luck.