I have absolutely nothing to support this but I assume that she didn't live in the brothel, because
That's a domestic dwelling.
It has cooking and food and probably also water storage facilities. And as we now know from Bad Boy, Kuchel also had her own fancy possessions that she hocked for food when she couldn't work because she was sick. That doesn't sound like someone who has no autonomy and was completely under the thumb of a pimp.
I think it makes more sense that it's her own single room dwelling. The brothel, as tatty as it is, looks like it has some pretence of fanciness, the candelabra and quill and upholstered furniture, the dressed-up lady, something that her room completely lacks.
It's also the room Levi is shown to have continued living in after she died thanks to the bonus manga, something that would make no sense and I think would not be possible if it were a room in the brothel.
It also makes absolute sense why nobody was aware of when Kuchel died and why Levi was all alone. I don't have good pictures of the bad boy manga because I suck so bad at photo taking, but the table was next to a railing and Levi is depicted having tea with his mother while looking over the Underground, which implies that they're on some sort of outside balcony, something that would not be a problem if there was no weather ever to worry about.
I think Kuchel lived in her own place and went to work in the brothel.