Acne has nearly nothing to do with washing or what foods you eat. It's got more to do with stress and hormones.
It actually indicates a high level of testosterone, that's why you get it when you take 'roids.
If you get it during school it's probably because stress is causing your hormones to go mad.
The only thing that I would say to avoid is touching your skin with your fingers, this can help alot. Over washing can actually increase a breakout if you don't use the right products. Soap is very bad. Try using an exfoliater first to remove dead skin and then a gentle foam wash.
See a dermitologist, acne can be prevented but only listen to skin specialists, not normal doctors or your friends. There is sooo many myths about acne that ONLY a good dermitologist will help. Take vitamin A too.
BTW - Back acne is normally nobular acne (I think that's the name) and it's completely different to face acne, there is a drug called RoAccutane (concentrated Vit A) that completely clears up ALL kinds of acne but the side effects are bad and it's very expensive.
As for if girls care, offcourse they do however the good news is they don't care nearly as much as boys care if girls have acne. Remember sometimes we look at ourselves and think that a girl can't find us attractive because we look at ourselves the same way as we look at a girl (through male eyes), not all girls like the pretty boy look, they look too feminine for most.
Remember look at all the holywood stars who have acne or bad skin, Keanu Reeves, Brad Pitt etc - They don't do too badly.
