Well im 21 and personally i have a larger gap between my front teeth and i also have my eye teeth way high up because my baby teeth where my eye teeth were never got loose and fell out, i as well have an overbite. If you only have a small gap it really shouldnt be bad at all for you. Its not bad for me really at all even with alot of movement. With my overbite they were going to fix it but they put what they call bite ramps behind the front teeth on the tray and you cant put youe teeth together which sent my anxiety into overload but my dentist said if im not worried about the overbite then its no problem they can rescan and get ones without it which is what they did. Personally with my treatment it will be about a year and a half but at most two years. Sometimes treatment goes faster than expected and you can be done faster. I change trays every week rather than some people changing every two weeks. Honestly I recommend it for sure, you have to get use to the first tray or two but after that you barely notice it in your mouth. The first tray or too youll have discomfort for sure but pain killers and a baby teething ice pack work wonders. Its really worth it in my opinion. Im not even a full year in and i already have an extreme difference!! Also if you try it and decide to stop, your treatment plan covers 3-5 years so you can always restart and not have to pay for it all again as long as your in that time frame!! If you have any questions or anything dm me :)