Decreased breastmilk supply

So I did an unwise thing. But first, let me explain. In order to control my weight and other health related reason I fasted a lot (and counted calories). But after I got pregnant I went on a normal pregnancy diet(extra calories and vitamins etc). When my daughter turned 3 months I decided it was time to get back in shape so i started dieting and counting calories again and now I'm noticing a decrease in my breastmilk. I did a quick Google search and found out the horrifying truth. I mean i guess it makes sense but I was not thinking. I feel so stupid. Now i just want to know the quickest way to up my flow again. I love breastfeeding her. Any tips would be greatly appreciated.

Has anyone been through this?