Help!!!

I got drunk and slept with my manager! (This is why I don't drink!!)

I'm 23 and I am ready/do want a baby but not like this! Obviously if I get pregnant then that's fine and I will have my baby but is there anything I can do to kind of prevent it a little?

I'm not allowed to take plan B for medical reasons....

Last time I got pregnant I only had unprotected sex once (unfortunately I lost my baby) so now I'm worried that this unprotected sex will also result in pregnancy and I feel so stupid for doing it!!

I know if I am pregnant I'll have to do the whole pregnancy by myself and that will be hard after having a late term miscarriage.

Edit: I had protected sex on the 27th and also I'll have to do it by myself because I know for a fact he'll not step up to being a father. He has 4 kids to 4 different women.