Well me, personally, have not been in many relationships, and most of them have been short, but i've heard a lot and seen a lot of things like your situation. This girl Rachael that you like, must be something special to you. I want to tell you something, but i dont, just becuase if I mess something up, then it will be my fault, but you probabaly wont listen to a word i say, anyways, so here goes.
I think you should find out what pleases her. I think you should pleasure her as much as possible, whatever she wants to do, do it for her. Alos, you should let her know she is special to you. You should take her out somewhere really nice, or if shes the kind of party girl, take her to a really jumpin club or bar or something. Buy her whatever she wants, and hope for the best. WHen your sure she has had a blast night, just ask straight up. If she says no, just kind of look down, and play it off like you really want it, but you dont want to push it too far. This will make a female very unconfertable, just say its OK, and that you still want to continue to have fun.
My way might not work, but you can fuse some other opinons and things like that. Too bad we cant have a "block this member from viewing my thread" option