Take it slower.
It took months for my cats to even begin to like wet food.

I'm sure someone will come by and give you a lot more advice than that, but I
just wanted to pipe in that 3 weeks isn't all that long.

Adding water to dry food is a good step.  You could also try adding the dry
food to canned food.....a little canned food at a time.  The more moisture
your cat gets, the better.

Sue

I have a female former feral who wouldn't eat canned food. Tomorrow
is the second anniversary of her being with me. :)  She's only
recently started eating canned food. I tried all of the "tricks";
wet the dry food (she wouldn't touch it), mixed wet with dry (she
wouldn't touch it), withold dry food until she was hungry enough to
eat canned (she stressed out, pulled out her fur and overgroomed
rather than eat) so I just went back to dry and provided many many
sources of water to drink. In the last couple of months I noticed
she wandered around the kitchen while my other 3 got their canned
dinner meal. I started putting a bowl out for her, too. Just a
spoonful or so. Tried nuking it, then just putting in a bowl that
was rinced out with hot hot water so it sort of "melted". She
slowly has started eating what I leave her in the bowl. I still
give her a tiny bit of dry in a bowl away from the kitchen at
dinnertime so she doesn't stress out. But, she still goes back to
the bowl of canned and will eat at least some of it every night. If
she doesn't eat enough of the canned, I do end up giving her
another 1/8th cup or so of dry before I go to bed so that she
doesn't go without until she can be transitioned.

My cat was on dry C/D for 2 years and then had a second blockage which
required hospitalization for 3 dyas.
After that, the vet put him on MediCal Preventive canned food and no more
blockage even though crystals were found in his urine a few times.
Rusty is now on yet another canned prescription food for his diarrhea.
Good thing he hasn't refused any food so far.

Winnie