I'm not sure with how to deal with this, I'm not shy and I would say I'm quite confident talking to people. But when I hang out with friends for a long period of time (for example, when I slept over my friends house and hung out with her the whole of the next day, by the evening I just wanted to go home and I felt exhausted even though we didn't do much) I just either want to go home or for them to leave so I can be alone.
I don't really have any friends, these friends that I have mentioned are actually my cousins but they are the closest things I have to friends. I did have friends, but being around them became way too exhausting for me and I found myself always wanting to be alone.
How do I deal with this? I like hanging out with my family but it always ends up becoming too much and I want to be left alone.
I don't want to tell my parents about my social exhaustion as well as they'll say I'm anti-social or I'm just being silly.