I have been off depo for two months and my periods have returned and are reasonably normal, I am wondering if just because my periods have returned does this make me fertile or is the depo still in my system? Basically how long does it take to become fertile again after the depo injection?

How long the effects from depo remain is going to vary from person to person. Some women find they resume normal periods, and get pregnant within a few months of their last injection... many others find it takes quite a long time. Rough guide is a few months to 18 months... obviously some will fall sooner, some later. Having a regular period generally equates to ovulating as well, but it doesn't guarantee it... especially after just finishing off depo.