hey there, do you let the baby latch on at all when you're home? the latching on helps to stimulate supply. also baby can probably empty the breasts better, so the body knows it needs to produce more.
and on slow letdown at work, impt thing is to relax! It won't help if you're constantly stressed when pumping. Some ppl say looking at some pics/videos of your baby helps.
Another method that i remember reading about is a special weekend where you try to spend the whole weekend at home, and just let baby latch on/pump/do both as often as possible. that could mean every 2 hrly. drink lots of fluids and you may wanna rope in some help so you can relax a little.
all the best!!!