I suggest that you have a prolactin level done. If you feel uncomfortable having your psychiatrist order it, consider having your gynecologist order it. Elevated prolactin levels are possible on most antipsychotics, though Risperdal and Invega are most notorious for causing that. I think 1st generation antipsychotics are more notorious for causing this than 2nd generations, with the exception of Risperdal and Invega.

Are you also having lactation (leaking breasts)? That often happens with high prolactin levels. Mine leaked so badly that I had to put pantyliners in my bras. I also eventually had a pituitary microadenoma discovered from an MRI. All of these issues went away a while after discontinuing Risperdal and Invega.

It is possible that your lack of periods has nothing to do with medications. To get to the bottom of it, do consult with a gynecologist if your psychiatrist doesn't investigate it, or if your prolactin levels are normal.

The one and only good that came from me experiencing prolonged elevated prolactin levels was that my breasts increased in size. I went from a B cup to a C cup bra.

My periods are perfectly normal nowadays and have been for about 8 years on my current mix, which includes high dose Tegretol XR, low dose Lamictal, and med-high dose Seroquel XR.