My first daughter was a science project - she finished her 4 ounces of bottle in about 1 minute, when other babies we knew would be much more leisurely.  She cried when done, seemingly still hungry, but when we gave her more she threw it all up shortly after.  The doc said she had reflux and it was the discomfort that was causing her to eat too much.  After trying different nipples to slow her down, and different formulas, including soy which made her poop almost constantly, the doc suggested a tablespoon of rice cereal added to each ounce of formula which worked wonders.  She did this from age 3 mo to 6 mo when she outgrew the condition and we weaned her off the rice while starting the usual rounds of solid food for a 6 mo old.  We were worried about her gaining too much weight, which did not happen, and starting her early on solid food wasn't the issue we thought it would be either.  She's 15 now, and hasn't had ANY eating problems since this early condition.  So I offer this as a suggestion to any other new moms who are experiencing the same helplessness at easing their baby's discomfort.