Milk not coming in.

I had my son a week ago and my milk still hasn't come in. Baby's on formula but I want to exclusively pump for him. I pump every 3 hours and dont get a drop. Is there anything I can do or am I out? Sorry If this is the wrong group I just need advice. My lactation consultant from the hospital isn't there today. And she instructed me to pump every 3 hours. I feel no heaviness in my breasts or any change at all....