Currently the legs look like there’s no volume inside the pants–as if the legs don’t have adequate thickness. The folds/wrinkles must conform to the girth of the legs.
The shoes are misshapen proportionally and don’t conform to the proper anatomy of human feet. The heel/back is too large while the front/toe area is way too small.
The collar looks too thick behind the neck and does not crease correclty.
There’s no connection between the compression and stress point from inner bend of elbow to the protruding point of the elbow.
His left knee needs to be a stress point, but we don’t see it in that pant leg.
The compression point is at the bend of the waist, but you have the wrinkles/folds below that point instead.
His lower torso is either too long, or his pants are too loose and pulled down.
If you can’t find adequate references, then you must shoot your own references. Use family and friends or even yourself (tripod, camera, mirror), and get exactly the angle, pose, fabric material, lighting, etc right. If you try to fake things on your own, you’re going to make glaring mistakes. Only advanced artists who have extensive experience can fake things convincingly, and even they often need to consult proper references.
Beyond all that technical stuff, you need to also think about the artistic aspect.
What is the point of this image? What are you trying to convey? A narrative? an emotion? A statement? What is the premise? Will this be a complete scene or will the boy float in a flat, gray background?
