I would see a doctor about it,
It would be easiest to set up a calendar with Your doctor and a routine.
That way someone was able to have a better understanding of the dates etc.
I know it can be frustrating best to speak with Your doctor
I was on the depo for 1 cycle back in 05 (I think) and it really did a number on me. My cycles were so screwed up. At the time I had already had 2 kids and knew I could get pregnant quickly. Well TTC #3 seemed impossible after depo. I seen a doctor after awhile and was put on clomid. My doctor wanted to get me ovulating and get more regular. I took clomid for 3 months with nothing. Then out of the blue after almost 2 years I got my BFP!!!
How long have you been ttc??? I would honesly go see you OB and tell them how screwed up your cycles are. They might have a better way to get you back on track.
Good luck ttc and SSBD heading your way!!!