Infertility??

So I was on birth control for probably about a year off and on (depo) and then went off it for good which was around 2013 I believe. While I was on it and for a while after it I didn't have a period at all and then for the past year I've started having extremely irregular ones. Could this be related to the birth control or could it possibly be a sign of infertility?? My boyfriend and I are wanting to get engaged soon and then start trying to have kids young, so I'm really hoping nothing is wrong. Any advice or help y'all can offer would be much appreciated!