If you do the same things over and over again you cannot expect to get any different results. Sorry.
If you use old beans and then pregrind them at a shop then don't expect much crema.
It ain't the water, it's the old beans and the (lack of a) grinder.
Find a source for fresh beans roast dated less than a couple of weeks before use and grind them fresh for each shot and then tamp (even moderately well) and you will produce loads of crema. One caveat - loads of crema does not always equate to a yummy shot.
If you insist on using Illy then move to Italy where the Illy coffee is more likely to be fresh.
BTW those kids in the Italian shops probably pull more shots in a day than you or I pull in a month. They have skills, even if they're youthful. I'll wager they use quality grinders and grind coffee fresh. Really - that's the key.
Try fresh beans. Use a double basket and a decent tamper (it's easier, really).
The pictured shot is using an extra-big 18g basket loaded with 20g of coffee.
Drink the coffee, and don't feel guilty about "waste".
Think about it like this:
You will be helping poor coffee farmers make a living.
Cheers