The better the grade and the better the work, the better chance of getting choices.
Always... work as hard as you can for what you believe is important. If you want to go to the best vet schools, and be offered all the chances, you go for it! Sounds like you're already doing well! Good on you!
edit:
Yeah!! Extra curricular!! Volunteer at a vet if you can, or a humane society, an exotics rescue.. something to show you'll go that extra mile to get to where you want!
Be the best, the most outstanding person they can spot for their schools.