Can anyone tell me how to calculate the gallons of water in my freeform pool?

The pool is 32'long,and 23' at it's widest point(which is on a diagonal) and 3.5-7.5 feet deep.

Should I get a measurment from three differnt areas of the width, and then average that out?

So would the calculation look like something like this:

L x average width x average depth= pool gallons?

Am I close, or wayyyy off??

Thanks for your help