Try not to look too much into your cycle length. It is well within the normal range and I know alot of people who would kill for them cycles. Rather though.. look at your lutuel phase (the 2nd half of your cycle after you ovulate). The LP doesnt change. So I would say its your ovulation day is changing. Certain things can delay/stop ovualtion such as lifestyle changes, no exercise, stress.. so on so forth. Is there any chance you could put a link to your charts in here??

An egg will pop from the largest follicle which in theroy should be from one side and then the other. But it doesnt happen like that. You cant predict which is going to release an egg unless you have become crazy (like i was) and knew everything down pat after 2 years..

Also, I think its about 3-4 months before the depo comes out of your system.. if not more. Lots of people take 12 or more months to fall pregnant after coming off that shot.. so be prepared, as much as it stinks.. you could be in for a long haul. Also.. try and give your cycles abit longer to settle into a pattern.