Wood Pigeon Can't Fly

Hi. 10 days ago I saw a wood pigeon walking in my front garden, who desperatley kept trying to fly but only ever managed to jump or hop a few inches in the air and then fall straight back down. I left him overnight in the bushes thinking he might just be stunned, but in the morning he was still there. I managed to catch him in a blanket and put him in a cage. I took him to a vet, who gave him a check-up and x-rayed his wing and told me that it wasn't broken (there is one tiny broken bone on the tip of the wing, but the vet said this bone was not an important flight bone and would not hinder him flying). The vet said to give him some TLC for a week. It has now been 10 days and for that time I have been keeping him warm in his cage in my dining room, with fresh water and wild bird seed. For the first 6 days he didn't appear to eat or drink anything and his poop was runny and a bluey/black colour. I ordered some 'Kaytee Exact' off the internet and was about to start handfeeding him when all of a sudden, the next day, he started eating and drinking (there's no stopping him now) and I've noticed that for the last 2 days his poop is now a healthy consistency and is white & greeny grey. I let him out of the cage every few days to see if he is ready to fly but he still only ever manages to jump. The only damage I can see is under his right wing and just above his leg there is a circle (2 inch radius) that is missing all of his little white breast feathers. There are no puncture wounds that I or the vet can see. I don't understand that if his wing isn't broken what could be stopping him flying away?
Please help. How long should I keep him in the cage before I make the decision that he may never fly again. I have read 2-4 weeks but this is for a broken wing?