Have I lost my cat permanently?

So I adopted Lexi last June and have spoiled her and spent time with her each and every day. She stayed in my room for the most part and gradually made her way out. She is exploring the house more and more.
Over the past few weeks, she has taken to laying in my parents bed because she was mostly chased in there by our other cats and wanted to get away. Well, this has started occurring more often to the point where she is starting to be in there at night also.
My mom has not spent much time with her because she is my cat and does not want to influence her in anyway since she will be going with me when I move.
Well, she is now sitting in front of their bedroom door. I closed it so she can't go in. Have I lost her to them or is this just a phase? I know she knows that I am her mom, but I can't help but admit that my bed feels empty when she's not there at night. Is there anything else I can do to not get her so used to their bed?

I sure know how you feel! Most nights, Clyde likes to spend a little time in my mom's room instead of mine, and as he strolls off down the hall, I always say, "Goodnight, you two-timing little gigolo..."

In your case, though, it sounds like Lexi has found a place where she feels safer than in your room. Is she the only cat who sleeps in your room? If other cats are allowed to roam in and out, maybe Lexi's looking for more private quarters...

Closing her out of there seems awfully mean, considering it's where she wants to be. It certainly isn't going to make her love you more or want back in your room. What I do find is that cats will stay in a certain place for some time (days, months) and then go to a new place, then another, etc. and rarely stay in any one place forever, but they sure do always want to go where they're not allowed!

it could be a phase, or it could be she just feels safer in there and as she gets more comfortable she will find another place. I know here at our house, the kits seem to go through favourites. Like currently, Gwenie, who use to be my girl..is now a daddies girl..and mewls and waits and paces..til he comes home from work..

I only had door closed for short period of time. Otherwise, she is free to roam anywhere she wants, esp during the day. Only one other cat comes in here, but not often and usually he is on the floor.
I will let her go where she wants. It's just strange because the other three WILL go in my parent's room. So I don't know why she would feel safer in there. She is still trying to adjust to the other three and they still pick on her.

Yes, but they're still 'her' 'people' (other cats, same species). I had a cat once (along with others) who, when another cat she treated like garbage all his life died, went nuts and absolutely literally meowed nonstop 24/7 until we got another cat a couple of months later. She shut up about one minute after she was in the house and never did it again! Wouldn't you feel strange in a place where you were the only human?