Oo, I forgot to add - if your DD doesn't seem happy and seems like she does need more sleep then I would recommend a sling. My kids have both really loved being in a carrier and have slept well being close to my body, plus you can get stuff done at the same time.
I agree with Heaven that thinking about self-settling is pretty premature at 12 weeks... if at all! Some babies just don't. In her 12 months of life Phoebe has self settled a handful of times - the rest of the time she is fed or rocked or patted to sleep. I'm happy with this (most of the time, LOL!) so don't know why self-settling is put out there as the holy grail of parenting. Some of our snuggles/feeds as she falls asleep are the loveliest moments we have together!