Am I missing a trick? Young teen boys clothes.

[ThatRosePanda]

i have a 13 nearly 14 year old boy. He’s outgrowing the 13-14 boys clothes but his arms and torso are still too short for an XS man's t-shirts and jumpers.
Is there something I’m missing size wise? What do you do with your teenagers?
thanks

M&S and Next both do teen sizes up to age 16 online only

I brought sports clothes on adidas website age 15/16.
I found it hard to get clothes in the shops but named websites had better options.
My DS lives in football jerseys and shorts

Gap used to be good for this ages like 13/14 14/15 etc for basic t shirts and stuff. I buy vintage gap from vinted quite a lot. Otherwise next?