Cycle after miscarriage. How long to regulate

I had a missed miscarriage at 12 weeks in December and since then my cycles have been 50days, 33 days and this last one 27 days with a lunal phase this month of only 10 days !! I confirmed O with temping so I know it was only 10 days, and I've read that's not good. Why is it getting so short is this normal or should I see my doctor ? How long did it take for your cycle to regulate after a loss ?