I had placenta accreta and therefore had to have it removed under a general in surgery. Unfortunately there was still retained placenta 11 days after and therefore I had to have a D & C to remove the remaining products etc. It was agonising and I could barely walk and was very sick and on hard core antibiotics etc.
The second time I had retained placenta, again I was in pain and heavily bleeding, but not to the extent of the first time around, as this wasn't accreta. I was given antibiotics and an internal and external ultrasound. This time I was able to avoid a D & C and do a wait-and-see approach and let it expel naturally. It took several weeks and lot's of bleeding, but eventually came good.
FWIW, I had no issues whatsover with supply despite everything that went on with my body, If anything I had an oversupply.
OP, if you feel your blood loss and product is worsening nad getting particularly heavy, then don't hesitate to go back to the Hospital/Doctor, as it can cause infection quite rapidly.