pic below. Pregnancy possible? Never peaked according to OPK but did have ONE day of EWCM.

Is there a possibility that we could get pregnant this month? I never had a “PEAK or Positive” OPK test, but I did have EWCM for one day. We BD that day and the day before, is there a way that the tests can be wrong? Also, I had low back aches and mild cramping. My cycles are regularly irregular - basically every two months I have a bleed. But, now my CM went from EWCM that day, to watery now creamy and I’m still having some cramping. Any comments with help. Thanks 🙏🏼