Hi!
If you were my patient, I would advise you that your irregular periods may be a result of your medications. I would suggest that you check a prolactin level and a thyroid panel. It is also possible that you have a variant of PCOS---which is a catch-all term for a hormone imbalance.
If you want to regulate your periods, you might consider oral contraceptive pills--that may also help reduce the acne, and will protect your ovaries from developing cysts. When you are older you should have a complete exam to determine whether you have any uterine anomalies--they can be hereditary.
Hope this helps!
Dr B