Is it normal to not think about anything exept my crush?

nope i think about my crush alot too! its normal

Ofcouse its normal,
I had exacly the same situation as u had, but when i asked the girl she told me no, But i still think that u should ask her,if she will say yes,u may be able to get top in next exam by that feeling u would have on thos days as u know she is with u.