Hi,
Your poor son!! It must be worrying you a lot too!
I recommend you make an appointment and speak to the teacher. He/she may be able to help encourage different friendships etc. My son, 11, doesn't like football, but he has found some like-minded friends!
If you speak to the teacher, they can look out for any low level bullying, they can tell you if he really has no friends (my youngest has toldme she had no one to play with.... but when I'd been at school, I'd seen her playing with different children!!!) The teacher can also encourage new friends to play with him.
His height won't always be a problem!
Can he join any clubs?
My daughter (now 13) was described as 'a bit of a loner' when she was younger but now has a good group of friends. Children can change. I had to stop worrying about it..... and her friends are lovely!!!!!