Not too sure where to start, so I guess I'll go from the beginning:
I got my period when I was 14, it was regular and I could tell you to the day when I was going to get it. After a couple of years, it started to get heavier, more painful and less regular. Got to the point where I couldn't move or go to school for days on end because of the pain I was in.
When I was 18 I saw several gyno's and doctors, and was eventually put on implanon (the stick in the arm). This worked great for a few months, and then the same problems happened again.
So, went back off to gyno's and doctors, went through various tests and pap smears, and it was discovered that I have extremely low hormone levels (which apparently counts for my weight and acne). Went on a pill with one hormone in it (seeing as the normal pill ended up putting me in hospital) and things seemed to fix up.
During all this, I had a habit of bleeding through/after sex, causing my period to start for a few days, and would have a period every seven days (one week on, one week off).

I'm 20 now and I'm sick of all this cr*p. I have distanced myself from sex thinking it may be a problem, but I can't even use a toy without causing myself to bleed and be in pain! My cervix hurts afterwards for days.

Please someone, are you able to give me some ideas as to what might be the issue and what I can do? Because it has the doctors as stumped as I am - It's affecting my confidence and relationships :(