Not sure whats going on

I had a mmc in august, had my d&c 8 and a half weeks ago and af came exactly 4 weeks later.well yesterday I tested at lunchtime after drinking loads and got a faint positive but not sure if it's leftover hcg from my miscarriage.going by my cycle before the miscarriage I'm 3 days late but now I've started bleeding so I guess what I'm asking is if it's possible to still have high enough hcg levels to get a positive on a frer but still be getting my periods or if this could be a new pregnancy and now I'm possibly miscarrying again.sorry if I'm posting this in the wrong place but I need advice and can't get an appointment with the doctor for a few days.thanks x