I think it's worth it to get them both, but they are very similar if you are tight on funds.
Keep a journal of all the things she says and does and try to be as detailed as possible. Also include your actions and what you said. From there you can gauge what's going on. If you notice something positive....You give her a compliment on a new hair cut or something about her....she touches your hand slightly and says thanks....write that down as "She likes compliments" and take the opportunity to compliment her WHEN WARRANTED. Don't start complimenting her on EVERYTHING. Keep is subtle.
You know better than us what the positive signs are going to be in your relationship and the situation. So if you compliment her and she rolls her eyes document that as "SHE'S NOT READY FOR COMPLIMENTS" and stop doing that for now. The journal will help a lot and it can be typed. I typed mine for the longest time.
This is a pretty long ride so settle in and start working on somethings for you. What are you doing for you?
