I re read your post. My honest suggestion would be to detox from meth and get clean. Then present your medical condition to a physician and see what they say. An addictive personality being prescribed scheduled substances is the fear, I believe.
Could you possibley be depressed/anxious? Self medicating for these is as common as it is for add/adhd. And these conditions can also make it difficult for you to concentrate. An antidepressent may help you after you are clean and sober to deal with the issues as well. I'd stick with the selective serotonin reuptake inhibitors as a class of meds.
Really wishing you good luck on your journey. I know it is hard.
They must be concerned that you are abusing the drugs and your phrasing of being addicted to it probably does not help that. Doctors are ethically responsible for a patients welfare. I guess you have to present your case so that the balance leans in your favor for giving you the medication to help vs. harming you. Good luck