Rainy morning cup
If your weight increased to 20x your current weight, without changing proportions, you would be about 2.7x your current height, width, and depth.
…just like OP’s mum.
Have you tried a double out of a ceramic cup?
Even aside from the thermal properties, the cup material itself can have an impact on how the flavors come through.
Rainy morning cup
don't do it, don't do it, don't do it,