The dreaded express. FWIW I express more often than I BF as DH is SAHD and despite my body being very used to expressing, sometimes I will only get 80mls. It's frustrating but I find lots of water, relaxing as much as possible and also stroking the breast lightly before expressing works wonders. My biggest problem is getting to the let down stage. If I am stressed, this sometimes won't happen.

Good luck! I think it's a great idea for you to have some milk in the freezer just in case but don't let it get too stressful for you