Girl problem! What should I do?

I'm a 15 year old muslim, so I'm not allowed to date, but I can't help it. A lot of girls in my class like me, I just broke up with my gf and I asked her why she liked me she said "Your really cute, and you've got a great personality, your funny, nice, cool...." she said a few more things but I don't remember what they were. Anyway the problem is that I have had a huge crush on this girl named Natasha for a few years, I went out with my ex because she reminded me of Natasha, Natasha is one of my best friends twin sister and I heard she likes me. Normally I can talk to girls easily, but when I see her I become a stuttering fool and I become a klutz. We don't talk that much, everyone knows we like each other and they try to get us to talk. I was thinking of becoming close friends with her then asking her out, but that would be wierd because we went out last year. Should I do it anyway? Please help, I really really like her!