I wish I'd gotten a sex talk

I'm 20, still a virgin and my parents have never talked to me about sex. Unless you count "don't mess around with boys" as something. I took a health class in elementary school which only talked about periods. So, besides general knowledge of what sex is: penis goes in vagina, use condoms or birth control to not get pregnant, I feel like I'm still missing information? Like, what's my first time going to be like? Signs of STIs? How can I tell if I'm pregnant? It seems like I'm supposed to automatically know all of these answers at this age without having to google them. I've never thought about this topic before, but now that there's a chance I might actually have sex I'm starting to panic. Thinking about it makes me anxious. What am I supposed to do before he sticks his penis inside? What do I do once it's done? Lmao, I love my boyfriend a lot but I really don't want to 100% clueless. I don't want to say my mom failed to educate me but, she did.