Positive OPK but period starting

Katie 🇬🇧 • TTC 👼🏼👼🏼👼🏼 Low AMH

Hi, I had a MC on 10th Jan so unsure when my AF is due. been using OPKs since last week to try track my cycle..and had 1 day negative then 3 days high Fertility (no peak yet) and seems AF is starting. Has this happened to anyone else? What could it mean?