Ditto to all the others thoughts.... nursing is not easy, especially in the beginning. I never got a 3 hour stretch of sleep, that's actually pretty good. REST whenever you can. And don't listen to any moms who haven't nursed or to one's that claim their children sleep through the night. It'll only make you question everything.
A fabulous book... which is very easy to read for a sleep deprived mom is Dr. SEars "Nighttime Parenting." It reassured me on those nights when I thought I was loosing it. Also, LLLI's "The womanly art of breastfeeding." Both books helped me keep focus and confident that I was indeed doing a wonderful thing for my child. You will adjust, it takes time.
Stay in touch here. We all understand.