What Causes Irregular Menstruation After Coming Off From Contraceptive Pills?

Im 25 years old and have been off the contraceptive pill for a year and a bit. Whilst on the pill my periods were very regular. However prior and since the pill I have gaps of up to 3 months between a period. Is this ok? Or should I see medical advice? I'd like to know about fertility as in the next 5 years would be an ideal time for me to start thinking about a family. I have never been pregnant before, and even when I was reckless and irresponsible in my earlier years, I never got pregnant giving me reason to think I may have fertility issues. Please help!