confused and a little freaked out

So after 2 bfns (one at 6 days away from af and 1 on day of af) and after starting a very tampon worthy period i counted mysef out for the month. I had a period for 3 days then it abruptly stopped. Then a bfp!!!!!!  What!?  Im freaking out bc after 2 bfns and a period i had several drinks (and a few cigs which is dumb bc i havent done that since college) this weekend. Could this be real?