Im terrified that I might have an std or I could be pregnant

I had unprotected sex on December 31st at around 2 am so its about 3 days.We had sex 3 times that night and he came inside me all 3 times. I had a yeast infection before I had sex with him and when I got home the next day my vagina was itchy. Today I noticed some pink discharge. Im terrified that I might have an std or I could be pregnant. I dont know when my last period was because I am on birth control and I dont take it like I should. I set an appointment with my dr on monday but I need some advice on what it could be. The itching is irritating