How much should we be feeding our cat?

We buy her the purina canned food, in the tin? Well, we got her when she was 10 weeks. We fed her one can a day, half in the morning, and half at night. She's almost one now. She is eating the same way, and she always has dry food, but I'm wondering if we should feed her a whole can in the morning/night? She eats her breakfast, nibbles occasionally during the day, and eats her dinner. I don't feel like I'm depraving her of food, because she seems fine, but should we be giving her more?