Irregular after stopping birth control

So I went off of birth control about 5 months ago because we want to get pregnant soon. I knew I would not be regular for a little while but my periods are lasting like 2 weeks. It's unbearable!  Not much time to try to get pregnant 😖. So the period calendar says I would be ovulating in a few days but I still have my period. Is this accurate or would the calendar just be all messed up?