cramps & irregularly

okay. so i’ve had my period since i just turned 13 and i’m almost 16 now so you’d think that i’d have this under control but i literally don’t know what to do. whenever i’d get my period it would be all cool but then i’d get home from school and these cramps would kick in and i’d be shaking and couldn’t move bc the pain was so bad but i was never in pain at school, well things changed.i didn’t go to school for 6 months (i got expelled for the rest of the year for fighting a boy) and when i got back to school the cramps started to feel like they did at home, pins, needles, knives, everything. i still continued to shake and feel like i was going to vomit, one day my friends had to walk me to our health clinic because i basically passed out in the hallway from these pains. anyways ever since january of 2018 i haven’t had regular periods, it’s mid july and i’ve only had 3 of them and when i do have them i go through a 30 count box of super tampons and pads, they also last about 8 days and the cramps are probably the worst pain i’ve ever felt. i’ve discusses it with my mom time & time again and she doesn’t seem to care or even have any concern. i want to get on birth control to see if that will help but she doesn’t see why the point of it bc she doesn’t know what type of pain i’m in. she refuses to take me to the doctor and it’s not okay, i’m at my wits end with this and i don’t know what to do. any suggestions? m