I can't stop thinking about him...?

I dont know any girls that would make it that obvious. He should have some idea that you like him. Now i'm not sure if boys should ask out girls or girls should ask out boys. Personally i would prefer a girl to ask me out but thats coz im shy. But it shouldnt matter who asks who. In your situation, if he gets irritated with all the 'blabbing' then hes not interested (just my opinion). But if he listens with a smile then i'd go for it.