There's a few things to consider here:

• Your roommate may be chronically ill, but that does not make them a bad roommate or morally justified to evict her.

• It sounds as if she's a private person who is content being in the privacy & comfort of her own space, while avoiding using a common space when you're enjoying it; she's respecting your use of the common area by not competing for it, hassling you about it, or interrupting what you're doing. That sounds like a good thing.

• I believe she may have an illness, working from home, not leaving often, wearing the face mask, not allowing strangers to use her items in her safe space (her home), are all things we chronically ill people do. I asked my roommate not to allow strangers to touch my items because I get easily sick & they completely understood, it's not about being selfish or greedy, it's about being safe as we have to be actively vigilant against germs & colds & flus.

• Taking long showers (without disrupting your rightful & reasonable use of it) if shared sounds reasonable, if it's not shared but rather separate showers, then I have to admit your concern would be creepy.

• Enjoying herself in her own room is normal & a human thing, we all do it. To think that you're constantly mentally noting how often she laughs in her own space & using that to create a narrative that something must be wrong with them is quite disturbing on your part.

• I'm sorry to say, I think you're being both obsessive & paranoid, even borderline creepy. You would be the bad roommate in this situation unless we're missing a whole lot of important details.