Re: 11 week old having trouble staying on
Watch her closely, as she starts to pull away with your nipple still in her mouth, get your little finger in between her mouth/your nipple and detach her before she pulls. Maybe the nipple without shield is a little confusing and she hasn't figured out proper detachment? Oh, and use plenty of lanolin on your nipples till they heal, in fact you can put some on right before and right after feeding.
My DS is 5.5m, recently he started liking to pop on an off while feeding too. Happily he does let go first...but the point is he will latch back on and keep nursing on & off till he's full, so I bet your LO will do that too.