Pos/neg opk question

Lindy • Happily married since Dec 2012. TTC #1 since Feb 2014. Found out on 6/13/14 that I am due 2/15/15. We are overjoyed!
Got very pos opk's on 4/19 and 4/20. Negative opk on 4/21. So does that mean I most likely ovulated on 4/20?
​Thanks ladies!