Cycle Variation?

Kendyl • Wife • Stepmom • Auntie • Nanny • Finally a mama, after 2 MCs and 1 Molar
For the past 4 months my cycle has been alternating between 28 and 30 days. From November 2014 to January 2015 my cycle was 29 days (the 4 months prior my cycle was 35 days- stressful time.), then beginning in February it has been jumping consistently between 28 and 30 days.    
February- 28
March- 30
April- 28
May- 30 
My cycles used to be so regular I could predict my period on the 28th day to the hour. After two failed pregnancies in two years my cycle has been more irregular and difficult to predict (I have never skipped). It has been over a year and a half since my last pregnancy loss. Has anyone else experienced the switch in regularity after either a failed or successful pregnancy. If so how did you go about best predicting ovulation when TTC? 
Thanks!