Op you really have got to be proud of your son for what he can and is doing, not what he hasn't done and please stop comparing him with his peer group, he will make his own life, as others have said.
My DD, just 18, had many health problems when younger, including hearing problems, scraped GCSEs and went on to a Business BTEC. She had to re sit English Language GCSE last year, having missed it by two marks. It was her last chance on old syllabus, and required her to re do her coursework in a short period of time, which in turn caused her to take her eye off the ball in Business.
She has just finished BTEC, we think with Merits but not confirmed till summer. She is having a gap year to decide what to do next, although I doubt it will be uni.
I am disappointed that she probably won't experience uni, as our DS has done, and think ruefully of those missed 2 marks in her English, what difference it may have made. However, I also know that she is immature for her age and that she wouldn't cope with uni in the immediate future.
Like a pp, I can also see that my DD thrives on work in the way that she didn't with studying. I first saw it a year ago, after a few days work experience, she was coming home a different person to the one who came home from college. She then had an xmas job, and is now back with same retailer, planning to work for part of gap year whilst volunteering locally and then hopefully volunteer/travel abroad. She has a variety of ideas for gap year, is a young Guide leader and has been on Guide trips abroad and gets a buzz from earning her own money and being able to run a car. She is a fiesty young lady that we are proud of, regardless of what the future brings.
Interestingly, our neighbour, who has 2 very bright boys, a year below each of mine, and is pretty damning about university being non-negotiable, is desperate for her eldest, almost 20, to have a summer job now uni finished. However, she is also very snobby about retail work, implying it is below her son, who hasn't done a days work in his life! I think she expected him to walk into a proper summer job, but he has very little motivation from what I can see. My DD might not be as academic as her son, but she has a great work ethic, which is a massive plus in the current climate.
I do wonder what she will do, but am making a real effort not to nag her, but to let her work it all out for herself. I can see that nagging will just push her away.