You should start helping animals in other ways until you are old enough to volunteer! At 9 years old I started raising money for a local pet adoption center by asking for donations instead of gifts at my birthday parties. Also, if there are zoos in your local area, do some research about the treatment of the animals there. If you find something you don’t like, start writing letters to the zoo with your friends. There are many things you can do on your own until you are old enough to join with a charity!
I think that you have to be around 16 before they’d let you do work on your own.
I have the same problem :/ I’m 15 and want to help by volunteering at the local vet (I want to be a vet when I’m older 🙂 ) but they say that I have to be 16 before I can volunteer. But I think you would be able to volunteer at an animal shelter if you went with some older friends, siblings or your parents. Hope it helps 🙂