Breast milk supply

Has anyone else had a drop in their milk supply at 6 months? I’m pumping while at work & breastfeeding when I’m with the baby. Except at night, hubby will give her a bottle so I can sleep. Lactation consultant co worker said to pump twice a night. I have done that but it’s seeming to continue to drop. We have introduced a small amount of solids but she doesn’t get a lot of volume. I used to get 16 oz when I was at work, now I’m struggling to get 12 oz. At night after I breastfeed, I’ll get maybe 3 oz total off the 2 pumping sessions. I pump 20 mins long every 3 hrs at work. I haven’t had a chance due to work & only having one car, to go to breastfeeding support group, so I don’t know how much she is taking at each feeding. It’s so sad to not have much come out 😕