Thanks for writing in.
I would like to inform you that normally, there is a difference in the size of testicles. However, to confirm that this difference is normal, please get an ultrasonography
of the scrotum
done. If the difference in the size of the testicles is >20%, then we need to look for a cause. Anything less than that ( i.e. 20%) is normal and need not worry you.
I hope I have addressed your concerns.