Truly I wouldn't worry about it - if these kids were stupid enough to try and hex you because you hit on a boy then they're not the sort to be able to raise much power to do very much about it anyway.
For a start, as has already been said lots of times, wiccans don't DO that - if they're playing with that stuff then they're not wiccan.
Secondly since they are more than likely young (that's meant nicely btw) they are not going to be particularly experienced at the kind of working you need to do for an effective curse or hex.
It's my opinion that you are scaring yourself into believing this, associating every little thing that goes wrong with these people, That has to stop :)
By saying 'I am hexed' you are giving in to any baneful energy pointed at you, you are allowing it to play on your mind and therefore subconcious which will be doing all kinds of nasties to you. If you take that out of the equation then you're halfway there to dispelling this stuff about hexing.
Hexing is so rare that it's more likely that you're the victim of a gossip campaign or whispers than actual magical hexing, even witches who've been practicing for many years think twice about hexes so truly - you're not hexed.
Shake yourself up and start thinking positively, turn it around to something good and 'of the light' if you like. Concentrate on you, empower yourself (new hairstyle or clothes or whatever makes you feel 100% on top of the world) you aren't hexed, that's for kiddies and very old witches (like me lol) not youngsters with all their lives in front of them!