Hi there blue. I'm ttc too! Very frustrating....My mind is currently playing tricks on my mind at the moment and I can't work out if i'm pmting or not!
Ovulation usually occurs 12 days before your next period. I too have irregular periods due to poly cystic ovaries. I am considering purchasing an ovulation kit. They can be expensive, but I think this will give me a better chance of conceiving. Just put a search for ovulation kit in google and see what you get.
The other way of testing if you are ovulating is (dare I say it) by checking your cervical mucus (nice :? ) your cervix will produce egg white type mucus when you are ovulating. Keeping a diary of this will help you determin where you are in your cycle.
During a typical 28 day cycle, the consistency of cervical mucus should be as follows:
days 1-5 menses
days 6-9 dry, or little to no mucus
days 10-12 sticky, thick mucus, becoming less thick and whiter.
Days 13-15 egg-white mucus ò thin, elastic, slippery and clear. Indicates most fertile time.
Days 16-21 sticky, thick mucus
days 22-29 dry mucus
i hope this helps! Good luck.
Xx