Hi! I'm 17 as well.
What's your reason for lengthening? I understand you may have done research already, but it's important to understand the procedure has risks and in general most doctors advise against it unless you're extremely serious about it.
I'm 5'5" and have suffered from height dysphoria since I was about 5 years old. I'm expected to reach close to my dad's height of 5'6", but I still wouldn't be content with that. I've known about stature lengthening for about a year and have it in the back of my head for when I move out, get a job, etc.
Paley has a plan where you can get 16cm, slightly over 6", but it takes three surgeries and costs $280,000. One can get you up to 3".