Worried mom

I just found out I am 4 weeks and 4 days today. I was supposed to start my period Sunday but I waited a few days cuz my period has been all over the place. I’m just worried because I was drinking over the weekend and was only a day before I was supposed to start my period. I know it’s not likely there was harm to my baby because women drink all the time before they knew they were pregnant but I feel scared and guilty. We weren’t supposed to start trying until next month.