What does this problem with my period mean?

Ok I will try to make this short. Ok so I'm 20. Started my period a couple of years ago. It has always been irregular. I don't have and I'm not pregnant. There was something wrong with my mom's mom's period and my sister also thinks that there is something wrong with hers. My mom had to have a hysterectomy but I don't know about my grandma. I have diabetes and anemia but I don't take anything for the anemia. There was also a problem with my Thyroid but not anymore. I get unbearable cramps. I have ped out twice, felt nausea,dizzy, lightheaded and fatigue. I've had a pelvic exam and an Ultra Sound done and they didn't find anything. So my doctor put me on Levora birth control and that didn't do anything. It made my period last longer. So this time my doctor put me on Zovia. I haven't taken it yet because it says to take it the first Sunday after your last period and I haven't had my period yet. When I get my terrible cramps I have to take 3 or more Acetomeniphen to get rid of my pain. My period can also be anywhere from exteremely light to exteremely heavy. Me and my sister both believe that we have Endometriosis. Our doctor won't listen to us though and idk what other doctor to go to. My cramps have gotten so bad that I have begged my mom to take me to the hospital but she won't. But I'm pretty sure that they can do something right? So my questions are what should I do and what can I do? I don't think I forgot anything...But I'm pretty sure I might have Endomitriosis... I refuse to think that this is bad cramps. It has to be something else. Also no stupid or immature answers please. So I guess it's your guy's turn. What the Hell is going on here? Thanks.