Hello, I always found it difficult to express very much in one hit, although I had somethign of a too much too fast problem when I was actually feeding DD!! Perfectly normal, you'll find you're able to express more as time goes on, you'll also learn the easiest time of day (or night) to do it!

One thing I found was really handy was learning to hand express. Sometimes it was more effective than the breast pump.

HTH