Excessive weight gain

So I was never sick even in the beginning of my pregnancy and have just felt hungry like all the time. I'd eat a meal and then be hungry about 2 hours later. I'm now 15 weeks and I've already gained 19lbs! I got on my scale and was blown away. I don't wanna obsess over my weight the whole time. I'm hoping my hunger will slow down a bit. I really don't wanna get huge. My last pregnancy I gained 51lbs! Any suggestions? Anyone in the same boat?