Ttc with irregular periods

Can anyone suggest things that may be able to help. I have irregular periods, they come every month, but it comes when it wants either start, middle or end. I've started taking Blackmore pre conception tablets to help, I have to take iron tablets soon too, I've used first response ovulation test last month to see when I was ovulating and af still came, this is the first day on this months af and I was wondering if there's anything I can do to conceive that may help me