"How can I tell if he wants to be friends with benefits or date me ?"

That's not weird at all, most girls go through this scenario at least once during high school.

There's no sure way to tell but from my experience these are the clues I've gotten

He doesn't want to be more than friends with benefits if:

-he's still talking or hooking up with other girls (especially if he tells you about it )

-he doesn't talk to you unless he wants to hang out

-he tells you not to tell anyone you guys hang out

-he doesn't say cute corny things guys usually say

-he treats you like "one of the guys"

and most obvious ... -he tells you that he doesn't want to be anything more than friends with benefits

but sometimes it's hard to tell what a guy wants in the beginning because most guys will automatically say "oh i don't want a girlfriend" because that's natural of a lot of high school guys to think, but if it seems like you two have chemistry keep going with it and you'll have a good chance of ending up in a relationship.