@Stridah
I personally have no problems with it being square - this has been dug out of a cliff, so there is no need for it to look like a 'natural' cave.
However, I think that it is simply a bit too big. I suggest that you make the top 2 rooms the same size as the lower 2.
If you really wanted to make it more compact, I would lose the top corridor and have the entrance to the top 2 rooms from the sides. I think it adds a slightly more realistic air to the claim that these were carved out of solid rock. No one is going to do massively more work than is needed. A bit, yes, because they don't want it to be strictly utilitarian, but at the moment there's nothing that really says "yeah, upmarket cave dwelling".