M.F.
I had the same problem after a couple months at work. You should be able to have just 2 pumping sessions. I did 10 and 2. You'll likely get the same amount of milk. You'll also be able to sit for a full pumping which may need to be a full 30 minutes. I noticed that when I went just a little longer at the pump, I would often get another "let down" (usually right at the 25 minute mark).
And when you go to pump, make sure you relax. Take some music with you, or just close your eyes for a minute or two. If you're feeling rushed and worried about how much you're getting, it might affect let-down.
Make sure you're nursing as often as possible when you're with your daughter. She is more powerful than the pump!
You might be able to nurse twice in the mornings (once at wake-up and once right before you walk out the door). I didn't have time for a second nursing in the morning, but since I was usually pretty full first thing, I would nurse her til she was full, hand her off to my husband (he'd burp her and get her dressed) and pump til I was "empty."
In the evening, you can nurse as soon as you get home and again at her bed time.
In addition to pumping at home in the morning, you might add it in the evening too. The whole time I was nursing and working I would add a pumping session just before I went to bed (do it the same time every night so your body will get used to producing milk then). The baby usually had her last feeding around 7, then went to bed for the night at 8 and I would pump at 9. The evening pumping gave me the extra I needed to fill all the bottles for the next day.
I think the books say something like 5 to 8 feedings a day to keep up your supply. If I counted nursing 3 times (once in the morning and twice in the evenings), plus pumping 3 times (twice at work and once in the evening) that gave me enough to keep her going until she was 6 months old, at which time she weaned herself.
On the weekends, put the pump and bottles away (except for that evening time when you pump before bed) and nurse, nurse, nurse. Since your body might be on a different schedule from the baby, you might need to nurse more often (even demand-feed if you must), but it will boost your supply for the next week.
Also remember that as she eats more solid food, her need for breastmilk will decrease a little. And, if you're using breastmilk for her cereal, you might switch to using water, formula or juice in the cereal so you can save a little breastmilk.
Also, what kind of pump are you using? If it's anything less than the Ameda Purely Yours or the Medela, you'll need to upgrade.
Hope this helps!
Feel free to email me if you want to ask more questions, or just want some support. Pumping and working and nursing is hard, but you can do it!