I'm getting more distant from my family

Idk if I should say I'm feeling depressed but I feel like I don't belong in my own family. I feel more at ease away from them or outside away from the house. Today, my dad, my stepmom and my stepsis decided to go to the cinemas to watch a movie without me. It's not like I didn't expect it. they invited me but I know my stepmom wouldn't want me to tag along anyway (she's just pretending to be concerned) because if I did say I want to, I know she'll just get quiet. Like everytime I talk she'd just go quiet, like she does want me to be there. And everytime I go quiet, she gets talkative. She only talks to me when she's in a oh good mood but she usually only talks with my dad and my stepsis which fucking sucks btw. It's like I don't belong in my own home anymore. Kinda feel like Cinderella lmao but I don't really get bullied, just ignored and neglected. Oh how I wish I can just move out of the house as soon as possible.