Help - Hyperthyroidism in Older Cats

I have a black&white cat named Figaro.
She's been my little baby since 2011 - She was a stray that had been eating scraps of food out of my friend's garage for a while. When I visited for Christmas and she was outside in the cold rain, I decided to give her a forever home.

Anyway, I started to notice that Figgy was getting really thin about a year ago, and apparently she has hyperthyroidism.
She wasn't a kitten when I got her but the vet has always said that her pupils and teeth look young and healthy. Now he is saying she can be 10+ years old, since hyperthyroidism effects a lot of older cats... She's always been a picky eater but now she won't hardly eat her cat food. She gets really excited about other foods though, specifically Friskies Party Mix treats, but I can't give her a cup of treats every day so I've been giving her chicken breast and turkey (not the seasoned kind that we'd eat).
& I give her transdermal medicine twice a day.

Figgy is still running around and the breathing doesn't seem labored.
She still purrs and wants my love and attention. More than usual, actually.
It's been really painful to accept that fact that she's getting old and will die eventually.

Is anyone else going through this?
She is so lovely and I know these things are inevitable especially with age but I'd love to know if there is more that I can do to make things more comfortable for her.

Our pets really do worry us.

Have you tried her with chicken? also maybe take her the vet if she isn't eating.
I also have a black and white cat and he has always been fussy with his food, he will only eat a certain type of cat food and even then he wastes it. I have started putting some of his treats with his food and he seem's to eat a bit more cat food now.

It's is worrying but my vet says he is a healthy cat.

Do you give him wet food or solid or both?
Figaro does not eat any wet food either and throws up a lot.

I suspected stomach or intestine cancer because of that, but everything came back negative.

Could she have a food intolerance?

My guy is +10 also, but still healthy thank goodness. He loves catnip and after getting that he has a bit of appetite and polishes off his wet food. He has i ams dry food available 24/7 as he doesn't over eat, gets treats and about a tablespoon of wet food 3 times a day but he's fussy about his wet food. Definitely wants it but then turns up his nose. Don't know if the cat nip would work tho as it affects cats differently. You could also try science deit food we used to give that to the sick cats at the shelter, cats love it and eat it up.

I give him both.

Must be worrying for you.