Q&A: Baby sleeping too much?

Melissa writes:

"I have a question about my baby that I almost hesitate to ask, but here goes...

First a little history:  My daughter was born at 36 weeks gestation by urgent c-section. (breech, low amniotic fluid, cord wrapped around her neck). I had been monitored at the hospital for decreased fetal movement earlier in the week and then we had the 36 week ultrasound where we found she'd need to be born that night!  It was kind of a terrorizing experience with a happy ending. She is now a beautiful, round, healthy girl of 6.5 months, 18 lb, 27" long.  Pardon all the info, but I'm not sure what's relevant.

I'm a first time mom who is slowly shaking off the terrifying circumstances of my daughter's birth.  Please pardon me if I'm worrying about something silly.

My question is about sleep. Not your typical question, but how much is too much?  How did your (and your readers') kids typically sleep at this age?

My girl started sleeping through the night at 10 weeks. She is breastfed for the most part (I work 2 days a week and can't pump enough for her so she gets 2 bottles of formula each if those days.  Also, she eats a meal of rice cereal (1/4 cup) at lunch and a veggie and a fruit at dinner (around 6 oz total) every day.  Now that she seems more satisfied with the additional solids, she is sleeping between 12 and 14 hours a night.  Also? If she sleeps 12 hours, she takes a morning and an afternoon nap of 2 hours each.  If she sleeps 14,
She takes an afternoon nap of 2 hours.  She will also usually take a 30 min catnap around dinner.  This means she's sleeping around 16.5 hours a day!  Can that be right?  Really?  She is cheerful and active when shes awake (wants to roll in one direction, sit up, walk while holding my hands or endlessly eat-no interest in rolling the other way or crawling.)  Everyone I've asked brushes me off and tells me they wished they had my problems, but I still feel like this is really weird.  Is she bored of me when she's awake?  Is she healthy?  I just need some data from other moms or dads."

Thank goodness we have the technology to do emergency c-sections. I'm glad you're both here.

Now, I think this sounds like more than the average amount of sleep for full-term babies by an hour or two. But still, bear in mind that there's variance in normal. My older one slept consistently about 90 minutes less per day than my younger one did. He just doesn't seem to need as much sleep, and he gave up naps a year earlier than his brother did, too. 

I do think that preemie tend to sleep more, based on anecdotal evidence from the preemie babies and their parents that I've known. One of my friends just had a full-termer after having a 35-weeker, and she was shocked at how little this second one sleeps compared to her first, who was basically asleep all day and night for the first year. So my suspicion is that this is a result of her early delivery.

The bottom line, though, is that if she's happy and engaged and eating and pooping and smiling and grabbing for things and understanding you when you talk to her, the amount of sleep she's getting is fine for her.

Data points from other parents of early babies? And if your kids slept a lot when they were babies, have they kept on sleeping more than the average as they've grown?