Help?

So I have been on the pill since 18 (for cramps and irregular cycles). Got off at 26 and got pregnant 3 months later. Breast fed for a year (so I didn't have a period for 9 of those months) and then got back on the pill. Now I've been off for 4 months but my periods are very irregular! I had a 28, 30, 26 then 40 day cycle! Is this typical for going off the pill? Us there anything I can do to make my cycles more predictable? I've been temping but have had varied results because my 2 year old gets up to go to the bathroom a few night a week.