I breastfed both my kids for a year each. What I realized that helped was eating more. Not more food. But a whole healthy meals. Also,there were certain foods i would eat that would help alot.
Also drink tons of water. There is a supplement that some women feel really helps, fenugreek. I hated it but friends swore by it. Worth a try. Your daughter might also be going through a growth spurt and nursing more often and going back to cluster feeding. It doesn't necessarily mean you aren't producing enough, she just needs more. You might be doing fine. Unless you're pumping and not getting enough or if she isn't gaining weight it's hard to tell.
My sister does this massage thing. She will wait a big meal, drink four cups of water, wait 1 hour then she massages her breasts. Then pumps.. she makes about 5-6 4 oz bottles at a time. Then 7 hours later her boobs are full ready to pump again
Staying hydrated was huge for me. When my periods started coming back I noticed my supply would take a hit. Best of luck!