Its very normal to pump less than a baby actually takes from the breast and so its very normal to see less from pumping (and to worry about supply). Its also very normal for the levels pumped to dwindle over time. However, a few bits of advice, since breastfeeding is supply and demand based, try doing 3 pumping sessions in your workday instead of 2. (I was advised to pump 3 times a day, if working an 8 hour day, even at the point where I was pumping enough for my daughter in 2 sessions.) Also, even with the pumping session before you go to bed, do be aware that the lack of night nursing will also diminish your supply (less overall nursing time).
Also, stress can lessen supply. And watching while your pumping can do that too (as you panic about it not being what you think it should, it slows down more...) All this said, o know that even if you are making less, and your baby is nursing less, as long as you continue to nurse, even if its only 1 or 2 times a day, you'll still make her milk. The good stuff in mothers milk just becomes more concentrated as they take less.
Make sure you are also getting enough protein in your diet. Nursing moms are supposed to get 65 grams of protein a day to make good milk.
Fenugreek (which is in mothers milk tea) can help your supply, but doesn't work for everyone. You can get it in tablet form at health food stores (henry's etc). It'll make your sweat smell like maple syrup. But at least you won't have to drink tons of the tea.
FYI - my daughter is now 2.5 and still nursing. I'm allowing her to self wean. As my own pumped supply diminished, I eventually stopped pumping and supplemented her "away from me" milk with soy (my choice instead of cow milk), but she continued nursing strong. She's gradually dropped to only nursing at bed time and 1st thing in the morning (bonding with mommy time) or if she feels lousy. All of this to say try not to stress about it too much and know that even if you're pumping less, she's still getting milk from you and still getting all of the wonderful nutrients and immunities from you. You can make the year!