You are right. Your bird should be fully weaned.
Are you sure that the bird is 5 months old - or is it 5 weeks old? You should verify his hatch date with the breeder.
Your bird should have been weaned and fully feathered a long time ago - 13 weeks max, or about 3 months. There shouldn't be any bald spots.
If your bird is really 5 months old, and it's not fully feathered, you should consider making an appointment with an avian vet, to rule out possible health concerns. Here's a link to find one in the US:
http://www.aav.org/
As long as your bird is eating on it's own, there is no reason to continue hand-feedings. Just be aware that most birds experience a small amount of weight loss during the weaning process. You may want to monitor his weight with a scale.
If you must hand feed, cut it back to one nightly feeding, just before bedtime.
Many people offer seeds to youngsters - I don't. Seed-only diets are very unhealthy. Imo, seeds are the last food you should be offering to your bird. Seeds are nutritious in many ways, but many are also high in fat - bad for caged birds. They also lack vital nutrients found in pellet diets and fresh foods.
Seed only diets are like bread only diets for humans.
Your bird should be given a variety of foods every day, including high quality pellets, fresh foods like veggies, fruits, cooked pasta, rice and beans, nuts, other proteins and some seed.
Pellets formulated for weaning, and unsweetened human cereals like Rice Krispies, Cheerios, and Chex very helpful when converting from hand-feeding to solids, and when converting from a seed-based diet to a pellet based diet.
It's important to offer a healthy diet while your bird is still young. The good habits that you establish now, will last for a lifetime.
Best of luck to you and your bird!