Anyone else?

So I miscarried last year in September and its now March and my period is still doing something wonky. A doctor suggested I have low progesterone and to get checked. I don't understand though because I used Glow to get pregnant. My period has always been predicted at 28 days I've never had a killer flow(not since I was a teen) and I took ovulation tests to double check Glow prediction and it was spot on. I have the breast pain and aches like progesterone is supposed to do as it builds up before period and the pain subsides with each period that comes. My periods even seemed to be getting back to normal but my last period was just light spotting and this months I'm 4 days late and counting. Is it possible even after all this time my body is still trying to fix itself after miscarriage or do you think it's low progesterone. Does anyone have low progesterone and could give me insight. Did anyone not get a positive test back right away? (I tested this morning and got -)