I wholly disagree, especially with the chewing gum comment. With her facial structure and sex, she needs to minimize load on the joint.
Am I missing something? Bite strength correlates with wider jaws, flatter occlusal plane, flatter mandibular plane. Want to take a bet that her masseters are weak as f**k?
Or are you saying strong-jawed women are ugly? Either way I'm really confused by what you mean. Even the thing about joints, our ancestors chewed tough food and nuts like crazy. Chewing on some falim for 1-2hours a day isn't going to do ANY damage.
No 15yo should be making surgical decisions. The time she's likely mature enough to make a major surgical decision like this is early 20s and it happens to be the time that she can be certain development has stopped. Strictly speaking, however, she'd be eligible for surgery next year but as we know many of those cases still relapse, even in women. There is one item it's VERY URGENT and important for her to be evaluated for right now: her transverse dimension. RPE can be done until the age of 16, after that her only option would be surgery and the risks that come with it. She should see an orthodontist now for evaluation and get a 2nd and 3rd opinion to be sure. Yes, even if you already or recently had braces because you don't get to roll back the clock here later. Orthodontists miss it all the time, especially the flashy high volume practices. Radiation at her age isn't wonderful either, granted it's probably a wash and CBCTs tend to be small anyway.
A&G are fine surgeons to consult but you don't need to. You definitely don't need to consult Sinn. For just asking questions, maybe start with a lesser known local oral surgeon to get the dumb questions out of the way. Or better yet a local dental school, the professors tend to be way more informed than most private practice oral surgeons. Then look for someone nearby who practices jaw surgery in volume for a more detailed consult. Every major city has a practice or two that gets most of the business, it's a niche industry now.
Looking at you, yeah you suffer from long face syndrome like many of us. If you don't have TMJ symptoms yet, then count your blessings and get it fixed sooner rather than later before you start developing problems. And watch out for symptoms of sleep apnea.
What's RPE?
Regarding not seeing these surgeons, I strongly disagree. I had nearly 2cm of recession and my local surgeon didn't even think I needed a sliding genio. Total joke. Speak with the top surgeons who are known for producing aesthetic results. Let them give you their opinion on bite and how to achieve a more normal look - which after all is what OP is after. It's not making a "surgical decision". It's diagnosing the problem and finding out what can be done and when.
Also, I have seen distraction performed on small children so actually surgery doesn't seem to have to strictly wait until early 20's.
Still really, really want to know why you not only don't agree with, but strongly advise against orthotropics. I've tried to do balance research on this and not nut hug, but I cannot find any evidence that contradicts the claims. Mouthbreathing will kill you, swallowing poorly creates fat cheeks, and weak bites lead to weak jawlines. By seeing an orthotropic specialist such as Mike Mew she at least has a fighting chance of improving the things that LED her to where she is today, even if it won't cure her. Then when she does get surgery the results are going to be more stable and hopefully better as she can direct what's left of her facial development in the right direction to create a nicer starting point, instead of straight down.