Very very late period

Hi ladies, so last month me & my SO BD a lot. We weren't necessarily trying to conceive but we weren't avoiding it either. Well I missed my period for July & was 15 days late until this morning. I usually don't drink but I did drink socially which ended up in me being lightly intoxicated & had a very passionate night w my SO 3 times in a row. (Tmi maybe) So this morning I woke up to extremely heavy blood & lightheaded. It scares me because for 1, I'm usually regular. 2, I didn't take a pregnancy test because I was scared of a negative & wanted to wait until Monday so I can seek my doctor. 3 and If I weren't pregnant then its a health issue as to why I was as late as I was. & 4 I really just don't know what's going on. So can ANY of you ladies please help & give me some insight. Anything that you guys may think?? ( & yes I'm going to my doc next week but I just need to hear some opinions until then) so scared 😓