After reading the comments & the jobs you have had done
Your water level soundn't keep on dropping, maybe after the first drive after having a water pump done but not after then
If It is the headgaket has gone, it sounds like cylinders to water system, this will increase pressure in the water system & can make other water system parts fail due to over pressure. you won't get any mayonnaise, could get missing, might only leak at certain temps so could pass a compression test.
If your not fully into mechanics, its similar what happens when you use a soda stream machine, the bottle being the water system & the gas being the pressure leaking from the cylinders.
To start with the basics, run the engine for a few mins & check how hard the top hose is, drive for 5 mins & check it again, repeat, if the pipe gets rock hard, I would say its the headgasket. Then go to a garage & have a sniff test done(some liquid that changes colour with exahaust gases) cheap & easy test with no stripping down
You might not know how to judge the hardness of the hose, if not try another car to compare
In regards to having the water pump checked, if you have an external leak you won't get water system pressure & the top hose will be soft, not a bad thing as then it could just be a badly fitting pipe then etc.
Thanks