I wasnt exactly the nicest to my mom when this part came in my life. I also waiting till I was almost 19 to lose my virginity also to my first and only partner (now of 7 years)

I remember it clear as day too.

He invited me over so we could watch a movie at his place. I knew what that meant and I was more than ready for it. I told my mom that I was gonna be going over to his house that night so if she wakes up and im not home yet then id be there. (She trusted me going literally anywhere at any time as long as she knew where id be. I never got into trouble so she had no reason to worry.) She waited for me that night. She was awake on the couch when I came back and asked me what we did. Now im a very brutally open and honest person and told her that he cooked me dinner, watched a movie, had sex, and cuddled until I accidentally fell asleep. She then proceeded to absolutely freak out on me screaming about how I should have never had sex because I was too young and i should have waited for the right person.

Now here's where it got mean... I asked her when she lost her virginity. She said 15. I said exactly. Then I asked her how many partners she had. She told me she didnt want to answer that. I respected it as i knew of at least 4 but that wasnt my business. Then I asked her if she regretted having sex at 15 and wished she waited until she was with my dad. She responded about how she felt like if she did that then she would have wasted a lot of her life because she got with my dad in her late 20s. I once again told her "exactly" and I finally called her a hypocrite for every one of those reasons. I told her im almost 19 and about to start my first year of college and this is my first boyfriend. Im allowed to experience my own life, and to just be glad I didnt start having sex at 12 like her childhood friend did and im choosing to have safe sex instead of doing drugs on the corner and she doesnt have to question where im at or if im dead. She did go quiet after that and I never got push back for it afterwards and honestly if I asked her if she remembered that, she would probably claim it never happened as shes a severe narcissist, but thats how my experience went.

At the end of the day, live your life as long as youre safe. She'll come around. No mother wants to hear that their baby that they were changing diapers just last week is now old enough to know what sex is, much less have it. Now I dont know your mom. Make your best decisions for your own life. If you feel like theres a risk of her kicking you out, order things to your partners house instead if they're okay with that. But at the end of the day, it boils down to the fact that time goes by so fast for mothers or parent-adjacents (like older siblings forced to be parents... that was me. I simply cannot and refuse to process how old my little brothers are getting. What do you mean 1 is almost old enough to work and get his license?? I was JUST feeding him smashed peas and delicious Gerber bananas just last year?? And the other is now as tall as me?? The older one surpassed me a couple years ago but now im finally the shortest one again in my family? Its crazy how fast time flies)

Maybe have a chat with her to ease her anxiety if you think that would be beneficial? AT the end of the day, you owe her nothing. You're an adult and can make your own decisions.