Been off the birth-control pill for 2 months and still no baby what is the problem?

i had a IUD for five years, when the five years was up in december i switch to the pill which i was on from early december til april... i recently discover that i have a thyroid problems which i am taking meds for now. me and my husband are having a lot of sex but yet i am not preggo! please what is going on.. Its almost July and i was really hoping to be preggo by now, any advice?