I understand your paranoia, but scratching a mole does not transform it into a cancer. It can change the appearance a little, and that's what you're describing.
Look, just leave it alone for a couple of weeks so it can go back to its previous state. Then show a dermatologist one more time. If the doctor is absolutley, positivly sure it's OK (which will probably be the case), then I would forget about it once and for all.
Or you can ask the doctor to just take it off so you won't have to think about it any more, if you think you're going to keep worrying anyway, despite reassurance.
Best.
Dr. Rockoff
Dr. R
Dr. Rockoff