Hi. My ds has Dyspraxia and was dx when he was 4.5yrs and is now 12yrs.
I think it would be good for the GP to rule out a urine infection. Quite honestly, if your ds has Dyspraxia, restricting drinks etc. will have little bearing on his toileting. He will achieve being dry, but as dyspraxia is a developmental disorder, he will be behind his peers, so best not to stress about it.(I know, easier said than done). Sometimes, there can be problems with soiling also.
Help your ds, by leaving nightlights on and hall-light and maybe the toilet light, then all he has to concentrate on, is going to the toilet.
Dyspraxia needs to be dx by an OT or a Paediatrician, so the sooner you see one the better.
Has your ds other difficulties? Dyspraxia effects co-ordination and gross and fine motor skils. So, his handwriting maybe messy, gripping pencils maybe hard, things that can affect his performannce in the classroom. When you see the OT, ask her to see your ds at school, so she can advise the teacher on ways to help your ds.
He may find dressing difficult-ie, buttons, zips, and be a messy eater.
Your ds will eventually master a lot of these skills, but will be behind his peers, so dont compare what his peers/siblings can do and what he cant. My ds can still not tie laces, so we buy trainers with velcro. You will find you become inventive with ways to help your ds.
Lastly, Dyspraxia can affect emotions-ie, dc can be irritable, tearful and get stressed easily. As your ds progresses through school, he will get tired much quicker than his classmates, as he is having to work twice as hard to follow instructions etc.
Waiting lists for OTs are looong, so keep on, till you get to see one. HTH.