Unplanned pregnancy

I recently found out I was pregnant on Saturday. This was an unplanned pregnancy, as I was on birth control. I recently had a miscarriage in February and I decided to get on the pill after then. I didn't want to take any chances of getting pregnant again. I was taking antibiotics last month for an infection. My boyfriend and I had unprotected sex one time- I didn't really think much about it but I completely forgot that antibiotics can counteract the birth control. Needless to say, I have been smoking and drinking quite heavily between then and when I found out Saturday. I immediately have stopped cold turkey since finding out the news. I'm terrified I may have caused some damage or harm to my child. Any advice?