My girlfriend does not allow me to go down on her

I've been together with this girl for around 6 months already. Everything is well, except, for when I try to go down on her, she resists. As I kiss her stomach when I start moving down she either gently pulls me back up with her hands or says she wants to kiss me and pulls me up. I haven't specifically talked with her about that, I don't know why. She is also really sensitive, in terms like everything is "ticklish", like at the ribs. Is it the same "ticklish" issue down there you think? Or is she just shy or something??!?! I really want to give her that pleasure and I don't understand why she won't let me. ANy thoughts/advice on that ticklish issue in general and on the going down part in specific?!?!

I think if this is bothering you so much then talk to her. ask her why she doesnt like it, maybe she is just paranoid about that area. is she inexperienced? this can cause her to be shy about that you know! it may be that she just isnt quite ready to be that intimate yet. after all you will see all she has!