Re: 8 month old frequent nurser & "failure to thrive"
My suggestion: fire the sleep consultant. Her advice to stretch out the baby's feedings is the absolute worst thing you could do for a baby when there is a concern about weight gain. Not only is it torture for mom and baby, because the baby won't understand why she's being denied nurturing and sustenance and will be miserable, but it's also likely to reduce mom's milk production. Milk supply is created and maintained by the baby's demand, and any time you mess with that system by spacing feedings out to some artificial interval, you're likely to end up with decreased supply.
It sounds like sleep is currently a big issue for you. You're co-sleeping, right? If so, where- in a bed, on a futon on the floor? Is the bed firm or squishy? Is dad always in bed with you and baby? Does dad have the option to sleep elsewhere in the house? Is there a clock in the room where you sleep? Do you sit up to nurse or have you mastered side-lying nursing?
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"