I'm exclusively pumping for my twins in the NICU. My boobs have gotten a lot larger I can feel the milk inside. They are super heavy. But it's just coming out in drops when I pump and I'm not getting it all out. It takes me 30-40 minutes each time I pump every three hours. And I get anywhere from 40-60 ml each breast depending on what time I pump. How can I make the rest come out without having to pump so long? Shouldn't it be coming out faster than just drops? I'm a first time mom. No experience with breast feeding.