There are folks out there with more experience but too fast of temp rise is actually hard to do in a hot water bath. So that probably wasn't the problem. I don't get much more than a cup of whey from a 2.5Kg cheese during pressing, but I'm thinking it is something in the make before draining whey. Too much rennet?
If you post your entire recipe, someone here will figure it out
Could even be something simple, like too cold temp at pressing. Hoop and Press Milled curds about 28ºC is where I got my best results
Try it again using Wayne's tips