still getting a faint positive after mc

I had a mmc in October along with a d&e. I had my hcg tracked down to 4 and then I got my period a couple days after so my doctor told me I didn't need to come back and have anymore blood taken. Since my mmc I've had two periods. I took a pregnancy test today and saw a very very very faint line. Could it still be left over hcg from my miscarriage? Any comments are greatly appreciated. I don't know what to think.