AF or miscarriage?

I'm really concerned. We had an ecropic pregnancy May 2017 and since my body has regulated (its been 7 months) we have been actively trying to conceive again. My periods used to be super light, and only bright red. The last 7 months I have been on time, but some months I'm almost only passing clots. And not small ones. The cramps feel like contractions, and of course the bigger the clot the more intense the pain. My question is, could I be miscarrying and not know it? Clotting has never been an issue for me and I track everything about my cycle. Is it even possible to "miscarry" but start on time? I don't think that I've had a new pregnancy every month for the last 7 months, but I don't understand how I have had so many reassuring test results and I've been using opk's and timing. I know they say that the stress of TTC can cause complications and putting so much focus on timing can work against you but I'm lost. So, so lost.