Anyone else got a lot bigger than their weight gain suggests?

[Dalesgirl16]

I was overweight before I became pregnant so have been careful and put on just over a stone at 29 weeks. But I'm absolutely huge now. I'm 5'3 so not tall but surely that amount of weight gain isn't what this looks like? I just don't get it. Ive gone up two dress sizes at least and my tummy is enormous. Is there any explainable reason why a person could grow bigger without the equivalent weight gain? Or am I just wrong here?

Water retention/ fluid build up rather than fat???

No idea why that wouldn't show on scales

It would show on the scales but water weighs less than fat so you might feel bigger (due to the fluid retention) but the weight would be less than expected because it’s not fat?

Thank you! That makes sense!