hormone imbalance

So the first day of my last period was march 16 but I'm not pregnant, the doctor said I most likely have a hormone imbalance and did blood work. I'm a little confused about if I'm fertile or not and a little worried because last night I had sex with my boyfriend and he came in me....any suggestions or ideas if I should get a plan b or wait it out cause of my hormone imbalance?!???! Please help 😫