How to control my period?

I'm 14 years old, & I've been having my period for about a year and a half. I got it 3 days before Christmas 2009. It's regular for a few months then its irregular. I usually use tampons (started about 2 months ago) and they work great on the first day but on the second day I bleed through a regular tampon in an hour. The third day I bleed through in 2 hours and the fourth day I can last about 7 or 8 hours. I'm starting high school in 2 weeks and my period is unpredictable. Last year in grade 8 I bled through really blad 3 times abd had to go home. ): Is this normal? How can I make my periods lighter? And how long until they are normal? I;m always scared I'll start and not realize it until it bleeds in my pants (although I usually start at the beginning of a day, around when i wake up.)