won_mummy, pump amount can vary with timing, stress, etc, so it's still normal. But from my experience, as long as you're deligent with pumping/latching (I read before that minimum 8 times a day in the beginning), it can slowly increase with time.
my #1 also kept increasing intake in the first few weeks. As long as they sleep well after drinking, should be enough. If they don't vomit/regurgitate, it means they're not overfed.