katie, get some out with your hand first, squeeze with thumb and forefinger on either side of your nipple, press down towards yourself and then pinch upwards, as if you were trying to pop a pea out of the end of the nipple! After a few tries you will get a squirt.
are you using avent pump?
Make sure the cup bit is right over your breast with no air able to get out. Also I know it sometimes feels like you can just pump and it doesn't get suction, don't know why, but kind of try and 'catch' it on the suction, do it slowly and just reposition your breast a few times to get a good position. Also lean slightly forwards and try to relax. You should then get a thin squirt into the pump, and it feels a bit painful, then this should give way to a softer feeling as the milk comes and the squirts get less defined, if you see what I mean!!
I found it incredibly frustrating at first, and never thought I could get any out, but you can, you just have to keep at it. like so many things with having a baby, unfortunately!
so let me know if it's working, be glad to help cos I have so been there!