IS THIS NORMAL?

okay so this is my 4th day since finding out im pregnant with my first! :) im overwhelmed with a mix of emotions but my question is.... im so exhausted the past two days i cant do my normal tasks without needing a break i just feel like i could fall asleep all day long.... also like i cant catch my breathe like im out of breathe often! im only 4 weeks.... is this all in my head or what!? is this normal? have any of you other mommas ever felt this way?