I thought the same as you at 15.
Mind you I wasn't diagnosed. After I got diagnosed, I just ignored my diagnosis for about two years, as psychologists misdiagnosed me, and even my diagnosis of NVLD came with a sorta misdiagnosis of schizoid/schizotypal. I'm always quite outgoing really, and I don't really have social anxiety per se, it's just once I hang around people long enough, they realize how weird I am and all my quirks and stuff, and then they shy away. I used to just think that it was the other people at fault, or not realize why my AIM friends decided to drop off the face of the Earth on me one day. So I go through periods of social confidence where I'm like "Yay everyone likes me" and then later after I find out people don't like me, I get "shy" or whatever, then the process repeats. So, I don't have any real anxiety about like, I don't know, walking up to people and talking to them, it's just once they find out how weird I am they no longer wanna be my friend.
Even in your situation, you're probably misreading social cues. Most people don't like being in 1.5 hour long conversations. I used to think if a person kept talking to me, they liked me, but now I know they're much of the time just doing it to be polite. At one point in my life, I had a big social group and a bunch of "friends" but then once they found out I listen to girly Japanese pop all day, after I rambled on to them about how car engines work for an hour, I found out they didn't really like me. I also found out some was like, sympathy friendship, not because they actually liked me.
So the ideas that Aspergers could be solved if you just "Get out more!" or be less shy is delusional. As a kid I was like the least shy person in my family. I'd walk up to like anyone and talk to them. But I didn't realize I was extremely weird. So yes, I can talk to people, that's no issue. The problem is, do people actually want to talk to me? That's my struggle. The biggest problem in Aspergers/etc is self image. How you see yourself isn't necessarily how the world sees you. After getting involved with a big social group, I thought I was a super extrovert outgoing cool person. But I wasn't.
So, be happy, and I don't know. Maybe you are good socially. I don't know. But at 15, I thought there was nothing wrong with how I socialized, too, now I know I was extremely wrong.