22 and in pain... My life is frustrating.

I have been miserable since I was about 10 years old. I had a very unstable family life that included alcoholic parents and mental, emotional, and physical abuse- mostly from my mother. To make this story VERY short, after 3 years of things spiraling out of control my mother shot and killed my father.  My younger sister and I were taken to my Grandmothers house where I lived for the next 3 years.
 
I was very traumatized and damaged by the experiences that I had lived through. It was court ordered that I receive phsychiatric evaluation and therapy. I was understandably depressed and my doctor reccommended a series of medications to treat my labeled "Post Traumatic Stress Disorder" and Bi-Polar/Manic Depressive" behaviors. I was even given Lithium Bicarbonate as a treatment. Things just got worse.
 
The only outlet I had through all my problems were my love of sports and most importantly horseback riding. I was also on the track team, soccer team, and swim team during my early high school years. I was so depressed that I rarely went to class but instead sat in the nurses station until practice. Everyone felt sorry for me and let me pretty much get by with everything.
 
I have been having problems out of my leg since I was about 15 years old. My left knee continually hurt but I usually ignored it unless my leg gave out which it frequently did. I went to an orthopaedic surgeon at the age of 16 but he told me that it was just flexibility problems and denied me when I requested X rays. Shortly after the visit I had a horseback riding accident in which I broke some ribs and my left ankle (tibia). I saw the same doctor that I had before and after making me choose whether I wanted to pin the break or let it heal in a cast (and would not give me his professional opinion to which was the best choice) and my leg was casted.
 
Although I wasn't supposed to be on my cast it hardly slowed me down. I continued to skateboard and even ride horses. I was excited when I went to get my cast removed. The next visit I returned with knee pain again. I wanted Xrays done so I told the doctor I think I may have hurt my knee in the accident. Thankfully there was another doctor in the room. He simply walked over and put his hands on my leg and said "you have a big lump on your bone". An Xray, MRI, biopsy, and two weeks later I found out that I had periosteal sarcoma, a rare type of bone cancer.
 
I never was very upset about my cancer situation. I didn't really care about living or dying at that point. I just knew I wasn't willing to lose my leg, which was a good possibilty. I made it through my surgery fine. The had removed the bone and transplanted cadaver bone which was held in place by a long plate and twelve screws. Later (a few days or weeks I can't remember because of the pain medicine) I was told they hadn't gotten all of the cancer and I had to have surgery again. It took me 6 months just to be able to walk right again.
 
I had different expectations of life after my surgery. I was glad they had saved my leg but had no idea how much pain I was going to have to live with. I tried and tried but after a few years gave up on the possibility of returning to my normal life. I became addicted to pain pills and became even more depressed. I had another surgery two years ago to remove screws that were backing out and also remove damaged cartilage.