mother and sister are seriously codependent

ever since i (25 f) was young my sister (26 f) has always seemed upset when i would go out and do things with my friends. she is autistic and she had trouble in high school but now she has a solid group of friends and they hand out multiple times a week. when i was in high school and i would have plans to go to the movies or the mall with my friends my mom would tell me to bring my sister or else she’ll be upset. i did once and she said she felt left out because she doesn’t have the same interests me and my friends do. they were kind and no one was mean but that was about it. i also feel like i can be more okay with my friends and be my true self around them then with my family. this could be because im adopted im still trying to work through that. now it’s years later and me and my gf are long distance so i go out of state to visit her (this will be my second time) and my mom tells me not to tell my sister about the trip bc it will upset her. it makes me feel guilty and sad and idk if im in the wrong. i genuinely have like 0 friends now im consumed with working i have no life outside of my gf i sleep and work and talk to her on a daily basis. on the other hand my sister goes go out regularly with her friends. she doesn’t drive or work and i primarily blame my mother for that but thats a different story like i just dont know what to do bc i plan on moving with my girlfriend soon and but i know its going to be met with a lot of guilt. my family is very dependent on my i pay bills and rent and i but groceries that i dont even eat weekly bc neither of them work. i feel stuck i want to move on but idk how