How can i convince my parents to have a dog?

You have certainly shown that you know how to care for pets even if you do not like them. Is there somewhere like an animal charity nearby, where you can volunteer to help with the dogs and learn to al them weekends? Then use the skill for walking elderly people's dogs. Your parents will then know from this and the way that you care for the birds that you can look after them. Do be aware of the expense of having a pet, you need to take out insurance and someone has to pay for for food, toys, blankets etc. Are you old enough to do a paper round to help with costs? Maybe with a friend to make it fun. A lot of sweeping up is also needed. Show you will help with housework. You will eventually convince them that you are sincere and know that dogs need work as well as being great pets.