Stomach Issues [ + Period ]?

Ok, so how many questions have I asked in the health department?
Well, believe me… I’ve had ALOT more questions, unanswered, than are in my Questions list..
Anyway..
This is really weird…
I’m 13… 14 in 4 months….. I’m on my period x P ….. But it was 2 wks late…
I am 100% virgin… But I suddenly just rest my hand on my stomach, and I can feel movement…… O_O
Could be because I’m hungry!!! But wtf ?! I checked online, some ppl say “Am I pregnant? I’ve already had a child, and it feels just like it..” but
I’m a VIRGIN… I’ve never had a virgin, I’ve had recurrent UTI’s …. And even if I was sexually active … Extremely heavy periods can often reduce the risk of pregnancy alot…
Sure, I masturbate every so often [actually, pretttty rare] …
So wtf ???
I’m probably just hungry, since I haven’t really….. eatn since 6 this morning … and its now 10:30 p.m…. >.> ………………………………….… [btw.. I'm not literally trying to starve myself, I'm just not hungry.. and if I eat, I get hungry too soon, and feel quite sick] ..
When I try to push my stomach in, btw [I'm a little bit overweight... >.> ... ], It feels hard, like I CAN’T push it in, w/o getting pains……. O_O;;;;;;
Help ?
Also: Any tips on convincing my mom to let me go on Birth-Control ?? My periods are absolutely INSANE… Its like a huge carnival, with 2000+ people, 5 – 7 days straight!! D=
See.. I can’t just come right out and say something.. I have to make up a different manor of saying it, or put it in text form [Notepad Document] …. She said “Whyyy? You don’t need it.. It doesn’t do anything….” well, she’s never been on it, and has never had hvy periods, so how does she know??? And my gma says “Uhhh…. NO. Its not healthy, it can really harm you,” …. wtf ………………
So yeah ?