Antidepressants and menstrual cycle

I've been on antidepressants for about 15 years for depression. When I saw my GYN last month and decided to start TTC she said to take them every other day, not a super high dose anyways. Well AF was due on Tuesday and has been a no show. Just took a hpt and BFN. Does anyone know if cutting back on antidepressants can mess with your cycle? And I better off going back to taking them everyday? She said it would be safe to take while pregnant (or very very low risk) (generic Prozac). TIA