I think you need to understand that PTSD is a very long, hard process, first. She can get help, and continue to work hard, but let me be clear: it won't make what happened to her disappear. Don't let this ruin the fact that there is hope. She can still continue to work towards being as symptom-free as possible. If you don't mind me asking, what do you mean by react wrong? If you're blaming her for her reaction, or asking her why she's reacting such a way with you, you have to realize that PTSD is very complex, and it has nothing to do with you. She clearly loves you tremendously, and I know it's hard to ask yourself "but I'm a safe person, why is she flinching away from me?", it's because she has been through a lot. If you feel rejected, talk to her about it (not when or if she's triggered - but later). Don't try to push the "why", but just listen to her. If she needs to talk, she will. Remind her that you're there for her, and remind yourself of all the things she does that proves her love for you.
You said you want to learn. Read. Read all you can, and this website is a great tool for that too. Understand her symptoms, her triggers (you don't always have to ask, just be observant), and you can learn through her. Learn by being gentle as you possibly can with her, and maybe ask her before you touch her, even if it's just a slight brush of your fingers on her arm, or holding her hand. In my last relationship, I made it clear to my boyfriend that I didn't like being touched near my neck for specific reasons, and told him to warn me before he approached that area so that I was prepared mentally for his touch. I have no doubt that she loves you, and you seem to love her just as deeply from your concern, which is a great foundation of support for her to get better. I think that right now, she is probably just as scared of hurting your feelings as she is of her own feelings. Have you talked to her about this? When you say she jumps away when you touch her, is it in specific places - or is it just general intimacy (eg, holding hands?). If you're touching her in a place that's triggering for her, then it might be easiest to ask her about which places to be more careful when touching her. If it's a general thing, I would ask her if it would be okay to work on little things with intimacy.
I know this is confusing, but I'll use my neck as an example again. I HATE people touching my neck, leaning near it, anything. I'm constantly afraid of having someone try to choke me there (from a previous trauma), so with my ex boyfriend, we worked on that a lot. He would touch my arms at first, or lean his head against my arms, and then he would kiss my shoulder. After I felt comfortable with that, I'd let him put his hand on the top of my shoulder, and then once I was comfortable with that, I let him massage my shoulders. After awhile and I was comfortable enough, I was okay with him touching my neck, kissing my neck, etc. Honestly, it's a long hard road, and you need to be very gradual with her so that she realizes that she is in a safe environment with you, and you can build trust with her.
There will always be "those days", but you seem like a truly supportive boyfriend to reach out and look for help so that you can help her. Good luck, and I hope you two work everything out. You both seem very much in love with each other, so I'm sending good vibes. Also, if she isn't already on this website, she should definitely sign up. I find this website helps me tremendously.