I would try to stick with it. Of course you can get burnt out easily. Going to school isn't fun and of course college is more advanced than high school. It may not be easy, but I promise it will be worth it for you in the end. I believe in you and you should believe in yourself. Don't let anyone get in the way of your dreams. I know you're passionate about animals and I know you have worked so hard. But, you have what just one more year? Just go for it, don't give up on what you want most right now. In the end it will be worth it, I promise. Also, maybe you can intern at a shelter if they allow it.