Chart help

Ok ladies I need help! This is my first month temping with long irregular cycle. I started temping in the middle of my cycle and this is what I have so far (cd26-cd44). I didn't temp on 4/20 because I would have only got about a half hour sleep but I did get a pos opk two days before that. My question is do you think I ovulated the 17(the first dip) and got a pos opk the day after or do you think I may have ovulated the 20(the day I didn't temp) or do you not think I ovulated at all? Thanks ladies!