I like to express milk in a bottle to see how much my baby is taking is that also breasfeeding or wil inot reduce my milk supply.

not a good plan: The best way to know baby is getting enough is to follow wet diapers. If baby wets every 4-6 hours it has to come from somewhere and is enough to supply his/her needs. You can never pump as effectively as baby can strip your breast, and this can limit your production some. I would let baby feed naturally and try to change the way you monitor things, spend the new time you get enjoying baby.

Don't need to know: We don't need to know how much a baby drinks while breastfeeding, as long as the baby is growing normally, as shown by the growth charts that track height and weight at each visit to the doctor. If the baby gets sick, irritable, or is not making wet diapers, the doctor can evaluate. In a baby who is not growing, we can just weigh the baby before and after a breastfeeding to see how much he drank.