Def look at your pump, as mentioned! I pumped with a Medela Freestyle that I took to work and used at home too. I used to pump a few minutes in the morning while putting on my makeup and sometimes, if I was lucky, while gingerly putting together my lunch box because I didn't want to tap anything and lose a drop--in my food :P I tucked the horns in my bra and it worked, I didn't use a special pumping bra or the harness contraption that comes with the Freestyle, it looked like too much work.
It's a good idea to fit in another pumping session while at home in the evening too. Another good tip I got was to pump at the same time, +/- 15 minutes. After the third day I had a lot of milk come in!
Check this out: