How many calories should I eat with exercise and trying to lose weight?

I have been trying to lose weight since April and have accomplished losing 30 lbs. I weigh 316 pounds and am 5'6" tall. I am eating 1500 calories per day. I walk 10000 steps, or 2 to 3 miles per day. Should I eat more than 1500 calories to be healthy? I have been getting hungry pains in my stomach and have also been very tired lately. I am wondering if I am not taking in enough calories because of the number of calories I am burning. Any help will be greatly appreciated.