Valproic Acid affecting my menstrual cycle?

I'm 13 years old, I've never had my period before, and I was diagnosed with 'petit mal' in August of 2010. I was prescribed Valproic Acid by a physician. Sources say that you should experience multiple symptoms about a year before you get your first period. I've experienced these symptoms for about the last year and a bit. Do you think that the Valproic Acid is stopping my first menstrual cycle from happening? (I just want to know before I jump to conclusions...) Please legit and serious answers only. Medical background and/or source(s) would be even better! Thanks so much!!