No idea dude - you need to ask your girlfriend. Here's two possibilities though, 1) If she is of Indian background also, maybe she has some cutural restrictions to kissing you? 2) Maybe she doesn't find you attractive. But, like I said, you need to ask her and if she doesn't give you a straight answer, tell her what your requirements are for a girlfriend.

There could be all kinds of reasons why she doesn't kiss you as much as you'd like her to. Don't make up stories in your mind because that will drive you crazy! As was suggested, talk with her about it. Without making her wrong or accuse her of something, let her know how much you enjoy kissing her and ask her if she likes kissing too. Maybe there are other ways she likes to physically connect with you. Listen and stay open.