How long will i have to have braces for?

So i got my braces 3 days ago and i was wondering how long will i have them for. I have an overbite, my teeth are a little overcrowded bc i still have 4 milk teeth so i have to wait till they fall out. The orthodontist said i will have to get teeth implants in a place of two of them. The thing is that i cant get teeth implants until im 20-21 and Im 17. My mom thinks i will probably have to have them on till im 20 so 3 years but from what i remember the ortho saying is that i got self ligating braces which are faster and i should have them on max 2 years and probably wear retainers later. My mom says she doesnt remember any of that so she insists i will have them in for 3 years and she wont listen to me when i ask why i got them on so early then.