DS is 10 and his handwriting is still very poor, he has had extra help at school and i have spent alot of time helping him at home. I sometimes wonder if he started as a left hander as when he was younger up to about 8 he did alot of things LH( apart from writing) but then started using RH for most activities. The school use the cursive style . His paed ( he sees for migraine) did mention that his joints are hypermobile, really backwards bending elbows! would this be a reason? but he has always enyoyed using lego and has had no problem with building models. I have mentioned my concerns to his teachers on many occasions but nothing is advised apart from practice and pen grips.
ds is hypermobile and yes it does affect handwriting . I'd suggest you ask for an ot referral and he needs to learn to sit properly supported, feet flat on the floor and maybe use a soft wrist support(like for a keyboard) or writing slope to give him a better angle (experiment with a lever arch file sideways on). ds was writing with his whole arm rather than just the wrist and hand and he found it very tiring and awkward.