Re: poor weight gain/length in 15 month old
I wouldn't wean her over this. Do you think that she didn't gain any height in those three months? Are all her clothes fitting her the same? Those height measurements are not very accurate when you have a squirrely toddler laying on a table. How were her head circumferance measurements?
I think that's quite a bit to gain in 3 months at that age - that's over a pound. My daughter gained maybe 2 pounds from 12 to 24 months. The pediatrician wasn't worried.
Why don't you think that your daughter is getting 16 oz of milk from you when she nurses those 4 times? She's more effective than the pump - you're pumping out 3 oz at a time, so she could easily be getting 4 oz or more.
Giving her cow's milk is up to you, but I don't understand how that gets her to eat more solids. Or gain more weight. Likely it will simply replace breast milk in her diet. My daughter had cow's milk starting around 14 months and really likes it... and upped her intake of cow's milk as my milk went away due to pregnancy.
It's pretty normal for baby to drop percentiles when they start getting mobile. Maybe I've never worried about my daughter's weight because she has always been tiny, but I think it's weird that it's considered to be a problem to be at 5% on the growth scale, but not at 95%.
Lilah 10/08 nursed 25 months
Beatrix 01/11 nursed 30 months