Hello, I have gone through the query and understood your concern. It is true that return of ovulation takes longer time after cessation of the depo shot, but, earlier ovulation can happen by chance. Since you already have a history of irregular periods and have come off the depo, you need clinical evaluation to see if your symptoms and the missed period are due to pregnancy. I would ask you to see a specialist, get a trans-vaginal sonogram and an estimation of the serum beta-hCG titres to confirm/exclude pregnancy and assess other causes. Hope this helps.