Egad, "not worry too much". Cats not eating are almost *always* an indicator
of something else going on. If she is not eating tomorrow, go back. A good
food to try is baby food (turkey or chicken no onion powder). It's worth a
try.

[snip]

We've found that if an inappetant cat will eat anything, he or she will eat
Hill's Prescription Diet 'a/d' formula (canned), which should be available
through your veterinarian. Don't be shy about force-feeding if necessary (we
use large plastic syringes) as an inappetant cat can lapse in to hepatic
lipidosis, which is life-threatening. A high-calorie supplement like
Nutri-Cal paste will also help to maintain energy levels and stimulate
appetite; squeeze dollops on the end of your index finger and then wipe it
on to the roof of their mouth. If, despite these efforts, the inappetance
persists, your cat is going to require force-feeding via a stomach tube and
further diagnostic work to ascertain cause.

All other things being equal, sudden changes in a cat's behavior or habits
are almost always indicative of an injury or illness. If your veterinarian
continues to be dismissive of your concerns, consider finding a new vet.

A cat who usually has a good appetite & now doesn't, along w/ not
eliminating, is a signal, IMO & IME, that something is wrong, & needs
investigating.  I'd suggest taking her to another vet, for a second opinion.

Cathy