@Cindy D – I almost cried in relief reading your story. I am 38 and I was becoming seriously convinced that I was the only one who took the route that you described. Just wanted to say I fully agree with Cindy and her perspective/input. I lived an almost identical life in the general life steps that she describes.
Also, re: the OP. I was always told/read that my ADHD (inattentive, Non-hyper) took more like 4 yrs off of a neurotypical developement. I found that to be fairly accurate in my lif, readiness and ability to adapt. If you consider a 17yr old to actually be 13 or 14, you may understand his reservations a bit. Life has expectations that not everyone experiences at the time that others feel they ought to. Deviate from the norm a bit in order to support your child. It’s ok if he takes a little longer as long as he isn’t just a couch potatoe, and contributes toward progressing his life and to your household in the meantime.
That may just be me though. My opinion only.