15 months not self feeding?

My son had his 15 month appointment and the doctor was concerned that he does not self feed or walk. My soon eats table foods well but only wants to be fed. I've tried putting food in his hand or cheerios on the high chair tray but he just drops them to the floor. He will grab my hand to move the spoon to his mouth only. Also he is not walking yet. Doctor says he might need physical therapy and I feel like a horrible mom. I'm failing. Anyone else 15 month not self feeding?