I suggest that you contact an LLL consultant and ask for a list of Pediatricians who are also lactation consultants. I think that this is VERY important because even though a regular pediatric doctor may be in favor of your breastfeeding he may not know how to handle the different situation that may come up. He might even tell you to combine with cereal or something instead of telling you how to modify YOUR diet or your nursing techniques in order to help your baby gain weight or whatever else is causing a problem.
There could be many reasons why Ana isn't as chubby as you want her to be. "Maybe that is just the way she is". Maybe she doesn't know how to suck correctly or hard enough. Maybe she just needs more frequent feedings. A LC is the key.
My daughter had problems at the begining and wasn't gaining too much weight. So I decided to co-sleep and now she has become a "betty boop" if you know what I mean, with all those night feedings. She is now 8 mo and is exclusively breast fed. No water, no cereal no nothing....just 100% mama's milk. And I intend to keep it that way until she is 1yo. Her doctor is also a LC and she agrees with what I am doing.
I let her suck on my breast even when she has fallen asleep because even though she is sucking for comfort she is also getting at least "some" milk that way.
You can try long feedings on one breast at a time. At least 20 min until the fatty milk comes in. Squeezing your breast while feeding also helps, it really does.
I also read in a Dr. Sears book that you can do short feedings on each breast alternating them every time the baby would slow down or get distracted. Burping her well and then going on to the other breast. This made the Milk Ejection Reflex work more rapidly so the fatty part of the milk would come sooner.
Also remember that if you do give her something other than breast milk...your milk supply will be less- Then you will REALLY have problems.
Don't pay attention to all those comments. Even though the mean well. I know that it's frustrating because it happend to me but I also know that the best milk in the world comes from mommy. And I have a healthy happy baby to prove it. People who see me breastfeeding her always ask: What else do you feed her besides breast milk. And I smile and say "Just the food GOD sent her...My milk".
Their jaws drop and they end up saying things like: "WOW, it comes to show that there's nothing better that breast milk".
I encourage you to keep up the good work!!! Everything will turn out just fine.