@Larisa yes it does look like the nest is too small but they will grow there until they are twice as big and half out of the nest. They are not so crowded as they look because they are mostly fluffy down feathers.
Following post #380 I was able to take this photo without getting on a step ladder and peering into the nest...so i did. Waiting for mom, she is near and i can hear her scolding me in the distance. By the number of poops all over the place it looks like the little hummingbirds are being very well fed