What now

So I always have had a 28 day cycle. This month though I was 5 days late which sucked because I was certain I was pregnant!

My cycle number is all thrown off now. My period only lasted three days and I’m certain it was my period as it was very heavy and I have miscarried before so I’m positive that was not the case.

How do I calculate when I’m ovulating ? We are going to try again this month any suggestions . I have two apps and they both have different days of possible ovulation.

Thanks for any replies