I don't misunderstand. You are renting an apartment with a bathroom; your apartment no longer has one. You can (with obvious inconvenience) use hers, but she excludes you during certain hours. I find it hard to believe that even if a court accepted "use my bathroom instead" as reasonable, it would find "except during these hours" to be dubious.

I am not in a position to advise you as to what will happen if you, of your own accord, "take extra time" to move out.