I've been on and off this board for fourteen years, but mostly posting for help when DS was at primary, when there were points where it really didn't seem as though we'd ever find a school that fitted. At one point he was advanced a year, we also home edded for a bit, there were social problems. He was reading 5+ years above age and 4+ years ahead for maths and found it mostly very frustrating.
He ended up at a selective school (scholarship and some bursary) but even then it wasn't plain sailing, got an ADHD diagnosis and I didn't think that he would ever properly reach his potential (and perhaps I was being pushy, had misjudged it, etc etc). But even so, being amongst peers and being taught to his level made a huge difference
It's now Year 13. He has decided what subjects he really likes (the GCSE results can tell you the one he didn't) and is forecast all A stars and has an interview for Cambridge. And also a small but fantastic friend group of supportive geeks who like the Smiths.
So to give a bit of Christmas cheer, I just wanted to say to everyone who is still in the long hard slog that is getting an idiosyncratic but highly able child through primary education, keep going. Lots of people on here will say 'let them be, they'll be fine whatever, it will all even out.' You almost certainly know what your child needs and, most of all, it does get better.
[What made me write this is that we just got the end of term report which is frankly extraordinary and did finally make me think that the whole insane slog had been worth it.]