Well I work as a vet assistant, I get to do all the things that a vet tech does but I'm just not licensed. I get to help in the lab, hold the animals, treat them, assist in surgery, help the doctors, ect. All in all I love my job, the worst part is dealing with the clients, esspecially when euthanizing, I can deal with euthanizing the cat, because I am helping it, but when the owner is there talking to the cat and crying it makes it harder. My favorite part is helping in surgery. I was offered this job so I could "test the waters" before I go to school to persue my DVM. As for you, if you can't stand seeing animals in pain or dealing with death than you are probably right about not being able to be a vet/tech. I justify it because when you make the cat feel better it makes you feel so good. We had a cat come in almost two months ago, she got stuck in a garbage truck and was in there for 5 days before a good samaratin spent 5 hours getting her out. Ms. Madonna had 3 broken legs and a degloving wound, you could tell the cat was in pain, but she never complained a bit (unless you forgot to give her babyfood!). We put splints on both of her right legs but her left leg (the one that was degloved) had to have daily bandage changes. Anyway, she is the sweetest cat and got her splints off two weeks ago, she loves to run and play and you can just tell she is so grateful, so even though she was in pain, I felt good because I was able to help make her better.
As far as other carrers involving animals, there are paying jobs at a handful of shelters.
You could also work at a kennel, though that would mostly involve dogs, more people board dogs than cats. You could even start your own kennel.
You could be a groomer or start your own grooming business. Then again, thats mostly dogs, though there is a lady here that runs a sucessful cats only grooming business.
There are also jobs available at zoo's and places like that, thats more big animals but I've heard that seaworld has a small program dealing with training and exhibiting housecats.
You could be an animal trainer, people don't take their cats to kitty bootcamp but there is a market for animals in hollywood, also, friskies has about 8 cats that they train and they take around to cat shows to promote their products, they have a nice little stage show.
Since you like nutrition maybe you could develop cat foods? There is a growing market out there for all natural foods.
There are a lot of careers involving animals, if you are still in high school you can go to your counseler, they have books that will list all sorts of careers involving animals, if your not in high school there are college financial planning groups that might be able to help you. Hope I helped a little bit, the possibilities are endless.