Definitely not! Babies are much better at removing milk from the breast than a pump is.
Many women want to know exactly how much milk their babies get when they nurse, and some will express milk with a pump to try and estimate this. However, rarely do women ever pump as much milk as their babies remove during a feeding. This is because even though current pumps are quite good at removing milk, nothing compares to the suckling of your baby. Therefore, don’t despair if you get less than expected. If all else is well (your baby’s latch, diaper output, and weight gain), rest assured that your baby is getting enough milk and know that the pump is probably underestimating your production. If you are still concerned, ask your lactation consultant to weigh your baby before and after a feed to know exactly how much milk he or she ingested. This is much more accurate than going by what you pump.