I think it also depends on your genes as well, as both my Nan and my Aunty (on my dad's side) both had to lose heaps of weight before they could get pregnant. I was talking to a naturopath about my cycles and about my Nan and Aunty, and she said that one ovary has your father's genes and one has your mother's genes and because i was only having a normal cycle ever 2nd month that my father's side was the one that was anovulatory....i thought that was quite interesting, although not sure how true it is....