I'm going to take a different track, since you feel you are at your wits end and this has been going on for 8 months - along time!
I'm wondering if he went through all of his developmental stages including lying on his stomach to gain strength in his neck, back, and shoulders; rolling over, combat crawl, and normal crawl. If the answer is no to even one of these, he may not have developed all the motor skills he needs including the ability to balance well. These are build during that first year of life, and all stages need to be systematically progressed through for full motor abilities.
If not, he may not feel comfortable walking due to poor muscle tone or lack of balance, even though he may be able to walk. Being carried is certainly preferable!
These stages of development are also important for neurodevelopment, required for the ability to focus attention, vision development, auditory development, and cognitive development - all of which make a child successful in school.
If this is not your son's problem, I am sure the other mom's comments will be enough for him to be right on track!
Good luck with your two kids - they grow up fast!
K. Johnson,
Mom of 3 ages 17-22
Author, The Roadmap From Learning Disabilities to Success