How do i convince my doctor i am responsible enough to take percocet for my fybromyalgia?

I have been diagnosed with fybro in 1994, when i was only 12 yrs old. I am know how and why this disease began. I was infected with hepitatis C by my dentist because my gums would bleed during cleaning and they used dirty tools on me. My body fought off the virus and left my immune system turned upside down hence the onset of fybro. I was told that I was the youngest diagnosed case in new england area and have been used as an experiment since then. I have been given 7 different muscule relaxers that didnt do anything at all and 4 differrent anti- depressants, like cymbalta that gave me unbearable side effects, Also tried lyrica and gabapentin - also with those the side effects were worse than the pain. I have gone to 2 diffferent physical theripists and i am currently trying accupunture which helps but only gives me an ok day verse day when i feel hopeless and immobile. I am only 28 yrs old and have degenerative disk problems already that casue severe shooting pain on top of the solf tissue pain, i also have rhemitoid arthritus and hypermobility syndrome. ALL thanks to the dentist. I have gone to every type of doctor known to mankind. I feel like i could get illegal drugs easier and that shouldnt be the way the world works. I drank alcohol almost everyday from 18-24 yrs old and that masks the problem of pain but i don't want to use alcohol b/c alcoholism is something my mother struggles with and i need to work to maintain a semi-fuunctional life so hangovers aren't dealable. I have never asked for a pain killer but i was already sent to a pain care office where they gave me anti-inflamitories for my arthritus and treated me like an addict for that! they also had me do out-patient surgry for injections in my lower back for the disks but that didnt really do anything either. Accupunture helps but i'm not a millionaire and can only afford it once in a while. I do not want to take percocet everyday, I want to take it when Im at the point of tears, so i can work. I think a good amount for me would be 30-20 pills per month so i dont understand how they could think i would abuse something i would only be able to use for 100 hours a month. Im scared to ask but im going to try a new primary care dr b/c mine left the office and quite frankly i dont have time to play games anymore, I dont know if i should just tell her my concerns and what i know will help or just play it through and take more useless drugs and more useless appointments? ....im desperate