I haven't hand-raised a kitten, but I know some folks here have used an eyedropper to get the milk into the baby.

Just keep gently trying. I know there are folks here that will have lots of advice.

One thing: kittens this young need stimulation to go to the bathroom. Wipe a warm damp rag across his/her anal area...hopefully that will stimulate the kitten to "go" - and then there will be room for food!

Call your vet for advice too.