I bought this tea a month or two into nursing my first child. She was often fussy at the breast and we'd been having real problems with green, foamy poops that nothing was clearing up (we'd tried "block feeding" to increase the amount of hindmilk that she was getting, but it wasn't helping and the problem was just getting worse--plus my supply felt like it was starting to decrease).
I started taking this tea as directed on the package (1 quart strong tea per day brewed with 2 Tbsp of tea) and our nursing problems disappeared literally overnight. The next day, she wasn't fussing at the breast, and her poops had turned that "nice" mustardy color and texture. I took it for a long time with her (until she was eating lots of table food too--probably 9 months to a year?) and never had another problem with her.
When my second daughter was born, I ordered the tea ahead of time "just in case." My milk came in much faster, and in great supply this time (my 4 year old is still nursing occasionally, which I'm sure helped). However, by the end of the first week and a half, I could tell that we were starting to get the same "green poop" problem. I started the tea again and by the next day, her poops had changed back to yellow.
I think something in this tea helps increase the fat content of my milk (my friend reported this result too--her milk changed color and got "creamier" looking after taking this tea). My supply was "okay" before taking it, and although it did feel like it increased my supply, I can't speak to whether it would bring your supply up if you were really struggling beforehand...but I think it's great tea and would certainly be worth a shot! Definitely more effective for us than the Traditional Medicinals "Mother's Milk" tea (which did not help me at all).