I looked this up cos I did a similar thing - got a BFN so went out and got drunk, a week later got a BFP.
Doctor said not to worry about it but I googled anyway, all of which agreed it should be fine as long as you don't carry on.
The worst scenerio was it might cause you to miscarry but straight away (and I only found one answer like that). Looks like your bean is sticking so try not to worry about it.
There are lots of people like you who don't find out for a couple of months (or even longer) that they are pregnant who go on to have happy, healthy babies.... x