What if I don't know the exact date of my miscarriage?

I think it was the weekend of 3/28 I didn't have ANY cramping just bleeding for 3 days. I had my first + hpt on 3/16. I was only about 3 weeks pregnant at that time. My levels have been checked they are now down to 188 from 1038. I am now cramping on and off a bit with light bown/pink spotting. Just wondering how I will know when AF is on her way and will this cramping and spotting continue until my next cycle starts....so many unanswered questions it's driving me crazy 😖😡😥