How to get my doctore to take my Endometriosis concerns seriously?

I am 21 years old and started menstruating at age 12. Since age 12 I have always had very long and heavy periods. In my younger years I would go threw a super absorbent tampon about every 2 hours or less. It has gotten a little better since I have had my son who is now 17 months old. I also have very horrible cramps and have prescription pain killers to deal with the pain. I am also on birth control to help regulate my period otherwise it is out of control and I can bleed for weeks at times. I am also with a man now that I have been dating for almost 10 months. This is the most serious relationship that I have had so this last 8 months or so I have been having more then I have in the past. I have been noticing that 3 out of 4 times it hurts and sometimes I have to stop it because the pain is unbearable. I also have pain after at times. The pain feels like it is in my uterus not my . I also randomly get super sharp pains in my lower stomach that hurt so bad that it basically paralyzes me. I am also having IBS and it hurts to urinate or have a bowl movement when I am menstruating. I have also notice blood in my bowl movements at times and I have had a colonoscopy that came back with nothing wrong. I'm just experiencing all these symptoms and my doctor doesn't seem to be doing anything about it. There is also a huge family history of this My mother at age 24 had a hysterectomy do to this my aunt at age 26 and my grandmother as well. My cousin who is also 21 has been diagnosed with this to. I really want a laproscopy how do I convience my doctor to give me one? I'm getting very frustrated. I have also had STD checks to make sure it's not that and I am completely STD free.