Breastfeeding mamas: any tips for boosting milk supply?

My little one is now two months old. Her doc is concerned she is not gaining enough weight. I am exclusively breastfeeding and pumping when I can but baby barely let's me put her down so that can get a little complicated...

I started fenugreek tea and supplements as well as brewers yeast in tablets and in "lactation muffins".

Any other ideas/tips for boosting milk supply? I am a first time mom and now I am a little paranoid about how much milk my baby is getting.

Thanks in advance!