Over weight and off birth control.

Well ladies I went off my birth control at the end of January.  And my first cycle was 20 days and the next one I went to my dr and got Provera and got my period after 5 days of taking it. I am also around 280 pounds and am just really nervous that myweight is what is cause my period to be irregular and I won't be able to conceive. I got an opk for this month and help pin point when I ovulate. I am also loosing weight and eating better. It's a long journey though. Any other ladies been here or have some advice.