Convincing parents to allow me to get my nose done?

If they are the ones paying for it then they have the final say. I'm sure it would be an expensive procedure and I can see where your parents are coming from. All you can do is try and talk to her again, just be calm and reasonable and let her know it's important to you. Until then, just try to accept the skin you are in. Everyone has their own body flaws, and you are still very young. Your body is still shaping and growing so if you were to get work done at all, I would suggest waiting til you're 18. You may not even want it in 3 years!