On mobile, formatting might suck.

I live with my mum and my brother (my dad lives about 30 minutes away) and consider myself to be very close to both of them.

We spend a lot of time together, but I also like to be alone a lot and as such spend a lot of the day in my room. We eat dinner together and watch a film or a tv show but then I disappear upstairs again. My problem is that they always seem to have the best time whenever I'm not around - I can often hear them laughing and chatting as soon as I leave, and whenever they go shopping together without me they come back beaming and clearly having laughed their heads off.

I'm not suggesting they're the assholes for having a good time, and I don't want them to not have fun. I just wish I was more involved, especially since mum and dad separated and the three of us have become a lot more tight-knit.

Whenever I bring this up to them they brush it off and say that I'm imagining it and I should just spend more time with them. I know that if I want to be included I need to spend more time with them, but I find it really hard to be around people for extended periods of time (I'm a big introvert) and I feel like I'm intruding as they clearly have less fun when I'm there.

AITA for thinking I'm the outcast of the family, and should I be making an effort to spend more time with them and be included?