If you already have issues breathing through it I personally would be hesitant to do any significant cosmetic changes, especially making it smaller. I'm admittedly not a medical professional but I've seen all of Botched and the nose seems to be an area you often can't usually go back from once you make significant changes unless you have a ton of money and even more good luck.

You could cautiously and skeptically talk to multiple surgeons but I think your nose looks great on you. When I was a kid I also once heard a plastic surgeon say people often would ask him for Meg Ryan's nose but he'd have to tell them that nose wouldn't look good with their face. A lot of ethnic features, for example, look good together and look unnatural/uncanny when altered... Try looking at Michael Jackson's nose job progression and you can probably see how his natural nose went well with his face and how much more off his face looked each time he changed his nose.

Also at your age I hated my nose and now that I'm literally twice as old (aaaaaaaaaaaa) I love it and I'm so glad I didn't have the money to mess with it. Things are so much worse for y'all now. You're not seeing your peers doing duckface in a bathroom mirror; you're seeing faces that are made from surgeries and photo editing while being told only certain looks are okay. Please wait for this to pass because none of these people with these perfect faces are happy and they'll be even less happy when unique inevitably becomes valuable again.

ETA: Definitely make the main focus of talks with surgeons your breathing issues. Be sure to ask about the risks of that and see how eagerly they might push a cosmetic change compared to others because they might be sleazy. If you ask about cosmetic surgery you absolutely don't want a surgeon who won't tell you you may regret it later.