Haven't read the other responses and dinners about to start so I'll make it quick. My milk supply decreased when my little guys was about 12 month. I was pregnant again, so that can do it. I would nurse all day and at bedtime, but then follow up with a bottle of milk (he was a year already). That way he was topped off.
A couple thoughts. Breastfed babies only need about 24 ounces of breast milk a day, I think. So about 5 feedings of 5 ounces. I'm not positive the exacts, but I seem to remember that. (Go to www.kelly mom.com for exacts). It's hard to tell how much they are getting. If you nurse first and then offer formula, she has the option.
My baby likes the playtex nurser drop in bottle.
Also if you want to increase your supply check out fenugreek.
And really the www.kellymom is a great site, I encourage you to browse it.
Good luck. Gotta run.