Re: 6wk not sleeping enough???
Several things come to mind here:
1. Are you certain that's all she's sleeping? Some babies get their sleep in catnaps, instead of in long stretches that look like "real" naps.
2. Are you reading that babies this age *should* sleep this long, or that this is what's normal for most babies? Your LO may have a different "normal."
3. At this age, it's normal for them to want to be held a lot (which it sounds like you realize). If she's not taking to the sling, is it because she can't see, or for other reasons? Maybe she can't hear your heart and needs repositioned a little, or doesn't like the smell of the cloth when she turns her head a certain way. (Someone gave me a sling which was later recalled due to infant suffocation issues--thank goodness my Happy cried in it, so that I never used the thing!(Please note that most slings don't have that issue.))
4. Is there a chance that your LO is overly-sensitive to caffeine? Not much of what you drink gets into your milk, but you never know. There's a lot of good caffeine info here on the LLLI site.
5. With Daughter the Elder, I would sometimes put her in her carseat, set it on the washing machine, and hold it steady while I set the washer on spin. That would often get her to sleep. Sometimes getting in the car and taking a drive would work, too. (Couldn't have done that this time if I had needed it; didn't own a car for the first year!)
These are all shots in the dark; I hope some of it helps! (And if not, maybe someone else can suggest something that will!)
Happy Toddler, 19 months, still bfeeding
Late Son, passed at age 8, bfed 5 months
Daughter the Elder, age 19 yrs, bfed for 22 months