Sleep... or lack thereof

Had you walked into my bedroom at 11:30 this morning, you would have found mom, baby and dad all sound asleep in bed. This was not the plan. Wilhelmina is generally a good sleeper at night so I have a standard routine. She goes to bed late between 1 and 2 am since Ben doesn't get home until midnight. He usually puts her in her crib and we go to sleep soon after. I will get up to feed her just as it is starting to get light between 6:30 - 7:30. On a good night, she will go back to sleep until about 9:30 when I get up to feed her. After this feeding, I leave her in bed with Ben who watches all her cute faces while I have breakfast, check emails and enjoy some alone time. That ddid not happen this morning. Everything went as planned until I set her down next to Ben. I thought it was still early and her faces in the morning are so cute so I may as well lay back down and watch her. I woke up 2 hours later. Mina and Ben were still asleep.
By every standard, I am getting enough sleep. I sleep 5 hours, get up, then sleep 2-3 more. 7-8 hours each night - enough to make many parents (or even non-parents) jealous. But we still needed those extra couple hours this morning and I could still use a nap this afternoon. Why? I got by on much less than this in college some weeks. How am I getting enough sleep yet I'm still the stereotypical tired new parent?
Part of it is probably the interruption of my sleep. I haven't slept for longer than 5 hours in over a month now. And while Mina is generally a good sleeper there are those nights where she starts crying just as we're drifting off or she wakes up way earlier than I would like. That takes its toll.
Mostly though, being a parent, especially a mother, is exhausting. I spend about 4 hours or more every day just feeding her. And a large number of the calories I intake go into making milk for her, leaving me with less energy (also less weight - bonus of breastfeeding). Walking up the stairs with a 9lb baby to change several diapers a day is making my back sore. Also, I am always on call so there isn't much time to relax. While writing this, I am holding my baby upright trying to pull her very stiff legs to her chest to help her release the gas. This gas is responsible for cutting her nap short. I'm starting to understand how I can be this tired.
I have read and heard many times "sleep when the baby sleeps" but I forgot to ask these well-intentioned people how they trained the dishes and laundry to do themselves. I will have to remember that for next time. For now, I will be thankful we get as much sleep as we do, take care of myself the best I can (an epsom salt bath with some lavender oil works wonders), and try to enjoy these first few months of parenthood despite being a little run down. I know my baby girl will never be 1 month old again so I will watch her cute morning facial expressions as often as I can and treasure the fact she needs her mom's help to get rid of gas.