Extensive period

My period is very irregular and very extensive and heavy. I'm 12, have school, and I go through pads SUPER fast. I live with my dad a lot and he provides things like that, not my mom, so it's awkward. I don't know what to do and it makes me nauseous and tired and gives me stomach aches, but usually not cramps. Solutions or suggestions for any of this? My doctor suggested birth control a few months ago, but I'd like to avoid that. Thanks!