Is it possible to ovulate if you have irregular periods? Its been 3 months since my last on and we're trying to get pregnant,

You are ovulating, irregularity has nothing to do with that fact.

If you are trying to become pregnant then you should learn "Natural Family Planning" so you will know the best times for intercourse to achieve that end.

NFP methods are fairly straight forward, but require you to keep records of your daily temperatures and cervical mucus.

Depending on how long you've been trying it very well may be time to consult with a Physician.