Finding trousers to fit ds1 is impossible.
He is 8. He is Not The Right Shape for school trousers. I have tried the generous fit ones from BHS and found them HUGE on him, and all the normal size ones are too tight and won't even do up. He's not fat but he has some extra chub 
and he's always been the same shape since he was a fully breastfed 3 month old. I keep hoping he'll stretch out but though he has phases of being slimmer, he always goes back to his default shape.
We're now down to two pairs that fit, one of which he managed to catch on a tree yesterday while climbing so now we have one. It'll be shorts weather soon and the length doesn't matter on them so I can get the next size up, but Oh trying to please his teachers has been awful and he's gone in in jersey type trousers a few times. He hates getting told off. 
Girls' trousers in jersey seem to be acceptable but not for boys.? I don't want him to be uncomfortable every single day because someone somewhere decided stretchy/jersey trousers are not suitable. (I'm not necessarily talking joggers - but the sort without the gathered bit at the ankle iykwim?)
What do you do?