Obligatory pet carrier question

I know this has been asked before but I’m struggling, when I called the airline to book my ticket, they made it very clear that the diameters could not be exceeded, I found a carrier online that was only 1 inch off and she made it seem like that was not an option. how strict are these regulations? For carrier sizes, I have carriers that are about an inch or two over the size limit (Sherpa brand) but they’re soft sided. I feel like they would squish under perfectly fine. My cats are four years old and five years old 7 pounds and 10 pounds respectively, I have only found one carrier that is the size dimensions and it is so small I do not think my cats will fit in it, what do I do?