Re: LOW milk supply.
Definitely look at baby's output like pp suggested. If you do need to increase supply, you can also add blessed thistle in addition to fenugreek. kellymom.com has some good info on dosages, etc. I tried reglan and it definitely boosted supply but my ob refused to prescribe it long-term because there aren't any long-term studies on the effects of reglan on nursing infants. I now get domperidone overseas to sustain my supply. There are some threads on here about reglan and domperidone if you end up needing to try one of those.
As for being intolerant of dairy, there are some signs - fussiness, colicky, after nursing. My lo would arch his back as if he were in pain. I had to eliminate dairy for several months.
Hang in there mama!
Wife to my sweet DH & Mom to our miracle DS