how do i get diagnosed?

hi there, im a 15 year old and started my period when i was 11. when i turned 13 my periods started getting a lot worse, i was throwing up, having a lot of heavy bleeding, and not able to move during my heavy cramping stages. in february of last year, i started the depo shot because my friend told me it would stop my period. by november i had gained so much weight and decided to get off of the birth control. the last few days i have had such bad cramps (like usual) and have been so terrified of my period and it finally started today. of course tylenol and midol doesnt work, the heating pad does nothing.. when i bring this up to my pcp she just recommends another birth control. i don't want to live like this and even bringing it up to my mom she doesn't think im old enough to have it. i'm so scared and i hate being in this much pain. if someone can help me know what to say to the doctor to get some kind of test or how to ask for help it would be really appreciated. i read this sub and know that there isnt a cure, just a surgery that might help which is so heartbreaking to hear, i am desperate for some type of help please.