Does the capacity portion of the pool math calculator take into account slopes on the sides and from shallow to deep ends? And should I try to account for such?

We have a 40 x 20 concrete pool that's 9' in the deep end and 3.5' in shallow. The calculator shows this to be a capacity of 37,400 gallons.

However, when we refilled the pool after doing repairs, the water company's meter showed we only used 27,800 gallons. (Surely this is wrong, right?)

I'm attaching pics of the pool (before and during repairs, as the slopes are easier to see). I'm assuming the calculator does not account for slopes, and the water line runs about 4" from the top, so what capacity should we be using, inparticularly for SLAM?

And if we have been using 32k gallons, is this setting us up for failure? (It has only been a couple of days since we started SLAM. I'm just wondering if we need to go back to square 1.)

Thank you for any input.

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