Convincing parents

So, I’ve been wanting a belly button piercing, industrial, or nose piercing for the longest time, but I’m 15, and I would never do something without my parents permission because I hate not having their trust, and they’re my parents so I would never do that. But, my parents hate all of those piercings, and I want to be a pediatrician, which means that I can’t have any piercings that show. My mom is worried about that and is making me wait until I get a steady job that could allow me to get one, or have a clear one at work and a regular one at home. So that answers the nose piercing. But how do I convince them to let me get the other piercings/ to get them sooner. When I asked my mom for a belly button, she said very quickly no, but she would never tell me why, but I don’t want to rule it out completely. So if anyone has any tips or ideas that could help me convince them to let me get at least one piercing I will be so grateful and I will keep updates :))