Faint line after miscarriage?

So on October 18 I found out my baby had no heartbeat at 11 weeks. I took the medication to start the miscarriage and had it that night. I bled for 1 week and spotted for another. I had an ultrasound after that which showed a tiny piece left over which they said was so small I could just watch and see what happens but to go back if I didn't get AF by two weeks later. Well AF didn't show and DH and I BD'd a number of times during the wait. I had some weird brown spotting for two days but that's it. The day I had my appointment (1 month after miscarriage) I poas and got this.. Not sure what to think. I had blood done and am scheduled for another u/s next week but I'm curious what you think or if anyone has had this happen. AF still hasn't shown. Only other symptom is sore breasts.