Hi there,
Are you still breastfeeding? If so, then your periods could be irregular for until you are done.
It is not abnormal to bleed for 6 weeks straight, have no period for 5 months, then bleed irregularly, differently than before.
After each of my pregnancies, my periods were completely changed. It is disconcerting but normal.
However, the heavy bleeding starting 20 months after giving birth might be a sign of infection or miscarriage and should be checked out by a doctor. If you are sure you miscarried, then I'd not bother going. Assume that things will be back to normal soon. If you are soaking more than a pad an hour for two days straight, do see a doctor, no matter what else.
It sounds like you might have miscarried if you skipped a month. Is that possible?
I once went to an OB who normally charged $250. When he heard I had no insurance he charged me only $15.
I know doctors are expensive, but the longer you wait the more it could end up costing... and your baby needs you to be healthy so if you can, suck it up and just go.
Good luck.