your cat may still not be quite used to your new house.

also: as my cat got older...he became more fussy about his litter box...
even though i kept it clean.
i ended up getting TWO litter boxes and it pretty much solved the problem

Yes, I've heard that two litterboxes are helpful as some cats prefer to
urinate in one and defecate in another.

Is there anything or anyone (another cat perhaps) threatening her or making
her feel insecure in the house? If you have a multi-cat household and are
keeping the cats indoors, there could be territorial issues. Here are some
useful links. One sure way to defuse territorial squabbles would be to allow
cats safe access to the outdoors, so I've included a link on that too.

http://www.fabcats.org/spraying.html
http://www.fabcats.org/behaviour_pheromonatherapy.html
http://www.fabcats.org/keepingyourcatsafe.html

Has your vet done a full blood-panel, urinalysis and full physical exam?
If not I would find another vet. I have a male cat that if he stresses he
gets bladder infections. I think it's because he will not drink as much when
he stresses.

Try to confine her to a bathroom with tile floor, providing her own litter
box. If that's not possible buy the largest plastic dog crate/carrier you
can
for large dogs, a covered litter box, hanging water bottle and bowls. Set
all
these things up in the crate/carrier and place the cat in there while you
are away or unable to supervise your kitty. This will give your aging cat
her own territory/escape/hideaway from the other cats and will lower your
stress of cleaning up the mess. I sometimes have to place fosters or
boarders in these large crates if they are not well litter box trained. They
always go home with better litter box manners. I get comments asking what I
did to get them to use their boxes. I tell them confining them to an area
they would not normally mess in helps them use the box consistently, cats do
not like
to mess were they lay. Hope that helps. I prefer to keep my babies than to
re-home them.
Hugs and goodluck,

Gina

Get another opinion.

So when you come to the point in life where your situation causes others to
be at there wits end, will it be ok with you that they get rid of you?

Hi, again, Chris - if your vet has already done what Gina suggests and
medical reasons can be discounted, revert to him again and ask for a referral
to a behaviourist. An already-stressed cat has faced one move and another
move will cause even more upset. I'd let an impartial expert look at the
feline social dynamics of this household. I do understand your rationale that
puss would be happier as an "only cat", but then that has to be balanced
against the impact of another move and the ability to find the right home. I
hope all goes well - it's a complex area.