Irregular periods and ttc 1st baby

I was on birth control (many different kinds) for 9 years. Now my husband and I are trying for a baby! I got off bc in April 2015 and have had my cycles from 28 days, to 43, 31, 31, 34, and now I'm currently on cycle day 39 with a no show period (I also took a pregnancy test yesterday and it was -). Any body have something similar to this happen to them? I know I've ovulated on CD 15 before because I took a test and it said I was, so I guess that's a good sign. But why are my cycles so inconsistent and long?

Thanks!