Help! No period.. not pregnant

Sarah • SND

I went off my birth control last winter. The last time I got my period was in March of this year. Last month my OBG gave me a medicine that forced my period on... it worked & I had an extremely normal period. However this month, again, no period... negative pregnancy test. I have an OBG appointment tomorrow.

Has this happened to anyone else? What could be the cause? Will this effect my TTC?