Yes it can be done under a doctors' supervision.
It can be done using medicines only since its just been three weeks, but if you keep delaying, it may cause problems.
Since you have already made up your mind that you want to abort it, I suggest you consult a good gynaecologist near you and discuss your problem with her. She will give you a few medicines, take those as directed and then it'll be over.
I hope it helps.