Fat bananas - I suspect you and I may share a son!
DS is 3b in reading and maths - 2a in writing (DD was 3c across the board at the same age). Remember being told in DD's day that a level 3 was impossible without cursive handwriting - which no one in my son's class seems to have been taught yet anyway. Daughter wrote much more freely once she could join up - it's easier on the wrist.
Boys are traditionally supposed to write less - but then, I was always told they read less too and that certainly isn't the case in my son's class.
My son is an avid reader - racing through books way too fast to get the best out of them. I get him to write book recommendations (like they sometimes stick to the shelves in Waterstones - much less like hard work than a book review). It makes sure he understands what he's reading - and also helps him with his writing.
2a is good though - I'm not worried. DS wants to be a level 3 though - he's very competitive already - but he does see his aching hand as an insuperable obstacle. I regularly hear moans of - "It feels as if my bone is bleeding" if he has to write more than a couple of sentences.