Learn English – How to say “now it holds” in past tense

I'm writing a short story, and came across a weird grammar issue. Here's a simplified snippet:

The holding cell was spacious, originally intended to hold a dozen prisoners. But now it held a single woman…

Now and held don't really agree because the first suggests present tense while the second suggests past tense. I could write "then it held", so then and held are both past tense, but I would interpret that as "first, the cell was spacious, then it held a woman and was no longer spacious", rather than "despite being spacious, at that exact moment the cell only held one woman".

I could also write "it held a woman", which would be accurate, but the idea is to differentiate between the past tense where the cell was designed (and presumably used) for a dozen prisoners and the past tense where the cell was holding a single woman.

This is similar to historical present tense, but I don't think it's the same. I feel like this is a common problem that has an easy solution, but I'm drawing a blank right now.

Can I just write "now it held", and it be obvious that now refers to "the point in the story currently being narrated" rather than "the point in time the reader is reading this point in the story"?

I want to show the woman's isolation and give the sense that even inside a prison cell, she feels almost insignificant, without saying that directly. Hence the contrast between a cell designed for a dozen prisoners and her being alone.

I'd welcome suggestions on better ways to write the sentences in general, but this question is specifically about how to say "at this moment relative to the narrative, < something >" in a concise, grammatically-sound manner.