Miscarriage - advice needed

I’ve miscarried. My last period was from Dec 13th-Dec 16th. I’m very regular with a 25 day cycle. I had a positive on Jan 2nd, Jan 3rd, and Jan 6th. I stopped checking. Until I saw pink discharge on Jan 11th. Then on Jan 12th, I had horrible horrible cramps in front and back with chills. I knew what it was. I passed a clot on Jan 12th. After 2 hours, the pain lessened. I continued to bleed as if my period was going on but with more intense cramps. I know I miscarried even though the test is reading positive. My question is: when does my regular period start? Do I count Jan 12th as my period date aka the miscarriage date? :-( thanks for advice. I was trying to conceive so this definitely caught us by surprise.