I'm in exactly the same boat as you! I visited an orthodontist at 16 about my overbite which at the time was 9mm. I have severe trauma to the roof of my mouth due to my teeth digging in. I get constant headaches, jaw ache, My jaw clicks, I bite my incisive papilla (the little lump at the back of your front teeth), I struggle breathing at night and I'm so paranoid about my teeth it's unreal. I was told at the time that my only option was to have jaw surgery and I couldn't have a brace, oh and apparently surgery could leave me with a flappy lip, so of course at 16 already having suffered horrendous bullying throughout school I declined. Now I'm 20 my overbite is now 11mm due to my wisdom teeth coming through. I visited my dentist last week regarding this issue and I was told because I declined surgery at 16 I would have to go private (probably costing me up to £2,000 and the rest). How they can expect a 16 year old to make such a life changing decision is beyond me. Anyway, my mum contacted NHS England, she knows exactly how much trouble I've had due to my overbite. They told her that your dentist might not tell you this but there is something called an IFR, which is an individual funding request that your dentist can put through to the NHS if they think your case is serious enough. I contacted my dentist and explained this to them and they said they will put a referral through for me. Within hours i was accepted for NHS treatment! And they even have a referral tracker. Now I need to point out that it is your othadontist who will decide whether you meet the criteria or not, but even being accepted for an orthodontist appointment at 20 is a bonus for me. I'm now on a waiting list which could take up to 12 month unless it's a medical issue (which mine is). So I'm just waiting with my fingers tightly crossed. It's going to be a long process, but it's a step in the right direction. Good luck and I hope this helps!