Birth control bleeding ?

I’ve been on the depo shot for almost 2 years now. During my last annual the doctor was surprised that I still technically have a normal period cycle. Though sometimes I can go just from period to period or skip one or having bleeding in between. Thought I sometimes bleed during what I assume is ovulation since it happens about a week to 2 weeks after my period cycle. Does this mean I have a higher possibility of maybe being the 1% that can get pregnant while on the shot? I know alot of persons don’t get a period while on it.