Third pregnancy isn't working out.

Hi forummers,
We have two daughters aged 7 and 8, and 5. Both kids came in the first round.
After trying for a third for 1.5 to 2 years, we went to the GP.
After various tests, it turned out I don't ovulate. I do get periods every 4 to 5 weeks though. Hormones are out of balance. The advice is to start taking medication to induce ovulation. Any experience with this here? About the cause? The doctor said sometimes your body needs a reset.
Still, I lean more towards further investigation into how this could have happened suddenly.