Hi,
Just wanted to say, despite the school assessing your son for dyspraxia, you should have a think about this again. The school test is possibly the SENCO watching him work and asking him some questions whereas the referral to an Occupational Therapist includes actual timed activities (writing, fine motor skills, co-ordination etc). Depending on how used your school is to dealing with additional needs (and there is a super-selective near me which has surprisingly - to me- low numbers of students with SEN) there's a chance the assessment by the school just might not be very good. Have a look at what dyspraxia is and if you think it could apply, maybe see your GP instead?
The reason I am saying this is because my yr10 son has been recently diagnosed and a lot of what you are saying chimes with me. TBF, the SENCO conceded that it was something that the school hadn't picked up as he is well behaved and was doing fairly well - despite one of his reports having EVERY teacher say "doing ok, would do better if organisation/presentation improved" or "written work poor but clearly understands as responds well to verbal questions".
As a result of the testing by the Occupational Therapist, he was then referred to a paediatrician (sp?) for a formal diagnosis. Some of the test results were shocking - below first percentile for some and quite frankly, I am so proud of how he's managed with basically no support at all for the first 14 years of his life. The OT also picked up on some physical things too which mean even without dyspraxia, writing would be difficult for him (but I won't go into them as I've mentioned them a lot IRL and would sooner not identify myself or him). The paediatrician is also looking into another condition, which may explain his loss of focus (it's one I'd heard of but would NEVER have associated it with my son). Like your son, teachers often say he doesn't seem engaged - although some seem to think seeming engaged is thrusting your hand in the air shouting "me miss, me miss!" - it's something I have mentioned to the SENCO as I think kids with different needs engage differently but it doesn't mean they're not engaging!
While dyspraxia is not something you can "cure", there are things which now make sense and we can mitigate some things. He's using a laptop for some sessions as his handwriting is so poor and he'll be able to use this for exams too (as one teacher said "I can't mark what I can't read") - obviously there is a limit to how useful this will be for things like maths. The most important thing is that I have been able to gain an insight into how his brain works. I know that he is intelligent and can understand complex concepts. He's got an affinity for maths and the sciences. But he is ALWAYS going to struggle with organisation and presentation. I can encourage him to use the calendar on his phone, set reminders for himself, ask if he wants help creating a revision schedule etc. And when I think he's not working as hard as he could be, I remind myself that actually, he's working differently.
He doesn't struggle with understanding at all - but he does struggle getting his knowledge on to a paper where it can be matched to a marking scheme. He's probably not going to get 9s and 8s in his GCSEs, but hopefully will manage (with support) to gets 7s and 6s - which in some ways seems a shame given how intelligent he actually is (although don't get me wrong if he got those results I KNOW they would be a good set of results in any circumstances - I'm not doing a faux-humble brag) but actually, considering his barriers they would be a triumph.
Sorry for the long post - as mentioned there were some things where I truly related to what you were saying and wanted to give you my experience. We would never have asked for him to get tested for dyspraxia - we just thought he had to make more effort - until someone with experience (not related to the school) mentioned it.