It could be that your supply is so closely in tune w/ your DD's needs that it's hard to pump any extra at this point. I found this happened when I was nursing & pumping for my twins. It helped for me to add in an extra pumping session at home every single day (even on weekends). I'd nurse them in bed in the morning (they'd usually go back to sleep - lucky them), then shower, then pump. I wouldn't get a lot of mik but over a week it would add up and help make up the extra they needed. And by pumping every day at the same time, my body adapted to having more milk available at that time. When supply was really an issue, I'd also add an extra session at work. I'd clock out at the end of my shift, pump, then go home (about 20 mins away). By the time I got home I had plenty of milk for them, plus had that extra pumping session's output for the freezer. Some moms will also keep up their pumping schedule at home over the weekends. You won't get much when you're nursing also, but you'll signal your body to up production and will hopefully start the week on a higher level.
As far as the pump, you can have the motor tested to make sure it's sucking properly. The store where you purchased the pump might be able to test for you; most IBCLCs have the equipment as well. It's unlikely that it has failed after part-time work for a year, but not impossible. The other pump issue might be flange fit. Your breast size changes over lactation and your size now with a nursing toddler may be smaller than when your DD was exclusively breastfed. Do you notice that a lot of extra areola or breast tissue is pulled into the tube along with your nipple?
I wonder about hormone levels, as well. Have you recently started menstruating? Your milk supply can fluctuate with changing hormone levels.
Also, is your DD drinking more of your milk while you're gone? My current nursing toddler mostly isn't interested in my milk when I'm at work, but when she decides she wants a bottle, she drinks a LOT. It's more about comfort and sucking than about a real need for the nutrition. You might ask your caregiver to focus on solids and offer a meal before offering your milk. You really aren't gone that much so your DD would be fine with less of your milk.
I reached a point with my twins where I could not let down for the pump any more. I'd only ever been able to get one letdown (sometimes not even that) and after about 2 years, my body simply wouldn't respond to the pump. I found that I could hand-express much more easily and quickly than I could pump. You might try some hand expression and see if it helps. I wouldn't sit at the pump for a long time without producing - that's just going to make you crazy. Take a break, do some breast massage, try again in 30 minutes or so and see if you can trigger another letdown. Often mood and stress affect our ability to pump.