My little girl is a week old & when I wake her up to eat she doesn't. She'll latch, suck a couple times & is back asleep. I do everything I can (rub her back, tickle her feet, nudge her chin, etc) & it doesn't really help. Should I let her sleep & eat when she's hungry or do I keep trying to make her eat every 2-3 hours? Dr was concerned about her weight, she weighed 6 7 at birth & weighed 5 12 four days later. I didn't think breastfeeding would be as difficult/frustrating as it's been. Please help.