This is exactly what happened to me. I really don't think health professionals understand cysts and how painful they can be. I had shooting pains at night, cramping pains, back pain and vomiting. This went on for months and (like you) I was put on a waiting list, although mine was 'only' 9 months.
At the time, it wasn't clear if my cyst was benign or not, so I was frantic with worry.
I went back to my GP several times (I got to the point where I didn't care what they thought of me) and demanded they contact the hospital.
When I had my cyst removed, they had left it too late to save the ovary as the cyst was completely wrapped around it. Mine was 14cm x 14cm (so I can't imagine the pain you must be in).
Oh, and the surgeon saw me the next day, she told me that she found "things floating in my abdomen and did I know what they were???" No!!!!! Turned out that it was poison and gunk coming off the cyst.
I'm now having problems with fibroids (does it ever end?!) and I've been a lot more vocal in getting treatment.
Seriously, just keep going back to the GP and demand to be brought forward. You need to be firm. I'm convinced GP's just don't get the pain that this causes and how it affects your life....let me know how you get on x