Exhausted!

I am exhausted! Has anyone else found this? With my first, who is now a 5 year old boy, I was bouncing off the walls, my only craving was roughly 8 pints of full fat milk a day. With the second (now!) I'm shattered all the time, no cravings or morning sickness, don't want to eat anything but salad as it makes me feel sick and the smell of food makes me want to throw up. Is anyone else experiencing the same?