why does liking someone feel so bad?

(English isn't my native language, so excuse any mistakes)
Hey Dads,

I wanted to ask this question, because I cannot really stop thinking about it.

I'm 22 now and a university student, doing a double major in physics & mathematics. Often because of that, I don't have much free time and spend mostly all my time in my dorm room, either to study or read.

I have never in my life held someones hand, been in love or had any romantic interactions. I don't even know if I want to change that.

My family is more on the conservative side and such topics were never discussed in our household. There was no puberty talk, no questions like "is xyz normal?" and there were absolutely no talks about, uh the other stuff yk. When I hit puberty I legit thought I had every cancer variant known to mankind. Mostly all my knowledge are from books or those cringy YouTube channels, which actually fairly helped.

It was always suggested that you stay away from the opposite gender in any other way than being friends. If I ever brought up a topic like that, my mom said I shouldn't talk about such stuff and seemed disgusted by it. I never talked to my dad about such topics. But figuring everything out alone was not easy, things like normally body changes or shaving or anything seemed almost impossible to do in the beginning, especially since I wasn't really allowed to have any kind of social media. I dress quite modestly and normally don't do anything deemed as "bad". I attend my lectures, I don't drink, smoke, go out at night, visit parties or whatever. But this kind of topic still lingers almost everday in my head. I feel like if I would kiss someone or be in a relationship, I would not be pure anymore, if you know what I mean. It's a weird feeling, because I had classmates who were casually hooking up with people or had open relationships and I would never judge or think less of them for that. That's why I just can't get it in my head. It feels like kissing or worse sleeping with someone would mark you and you will never be the same person after that, like kind of "used". I logically know thats bullshit and probably a byproduct of some purity culture type of stuff, but knowing these things doesn't make them less scary. I don't want to feel dirty everytime I think about such stuff. On the other hand I just have no knowledge or experience. I get really awkward when talking to others about such stuff, trying to just avoid it. The thought of having to take your clothes of in front of somebody else, actually might send me into the afterlife. I don't hate my body or anything, I feel comfortable in it. But when someone else sees it, it feels wrong. Like its disgusting and everything is wrong with it and stuff yk. I only really ever had one friend in high school, other then that my social environment is mostly just me. He, and his girlfriend who was in our class too, were really sweet souls though, because whenever we spend time outside from school, I could always ask them questions without any shame and they were really open about it. Never really gave me a stupid embarrassing feeling.

The contact sadly drifted away and we don't talk anymore. I moved to uni in a fairly liberal city after that, which was quite a change from a country side. But since im really shy in real life, I also found no friends in uni and just accepted that and spend my time alone.
Two or three months ago, I met a girl in a bookclub on campus. After that we went to the cafeteria together and talked for like 4 or 5 hours. Since then, we have met up every week, talking for hours and getting coffee. We watched the Odyssee together and after the cinema, we were walking the city at night and she told me the differences between the book and the movie. I think I could listen to her for hours, it just never gets boring. She studies medicine and is really smart and she looks really beautiful. We won't see each other for 8 weeks now because of the semester break we spend at home by our families. But this time has brought up all of the anxiety again, if I maybe behave weird or bad or something. If I do something wrong or if my behavior is disgusting. I don't know why this whole topic upsets me so much, I have never had that with another person. Mostly when I meet people, I just behaved like I always do. But with her I don't have so much trouble to come out my shell. I get nervous around her, which confused me too. With my friendship with my high school friend, I was never really nervous, it felt different. When I went with her to the Odyssee, which was our last meeting before break, I took the bus after at 1 am to my dorm back. I felt really happy, it was like having a warm fuzzy feeling inside. Since the break I still struggle with those questions though, if maybe what I'm doing is wrong in any way.
Thanks for reading this long mess o-o