Help please

So, today im going to 'drink' with my bf and his friend and i have been feeling pregnancy symptoms but im not sure im waiting 3 days to see if AF arrives so anyway he thinks all this symptoms are mental because that what his mom told him which made me feel bad because i know its not mental im not thinking that i want a baby or anything like that to be mental, so idk why would she say its mental so anyways if i drink and AF doesnt come and i am would that harm the baby??