How do know if you need a d&c

Two years ago in August I had a miscarriage... I did not have a d&c bc I was scared... So they doctor just kept checking my hcg.. Levels to see if they went down... Well my hcg.. Levels did go to 0... But my periods have never returned on their own since my miscarriage.., I have to take birth control, provera, or progesterone to have a period... I'm scared bc I think I should have gonna a d&c but I did trust that doctor...any suggestions