If you were my patient, I would recommend a couple of things. I would suggest that you try ovulation predictors, and a couple of blood tests. I like to do my testing this way: If you consider the first day of your period to be cycle day 1, I do an FSH, TSH and prolactin level on cycle day 3. I then have my patients use the ovulation predictors on days 11-16. I then like to do a progesterone level on day 21 to confirm ovulation.
If my patient is not ovulating ( irregular periods certainly suggests that someone is not ovulating regularly) I would then consider some additional testing for Polycystic Ovary Syndrome, and would consider starting her on Metformin and/or Femara to help her ovulate each month and therefore increase the chances for conception.
Hope this helps!