I've tried everything.

I'm stumped. Ever since I went back to work my milk supply has totally dwindled down. I pump on the way to work, when I get to work, during my planning, during lunch, and before leaving to come home. Also pump after every feeding at night and power pump before bed. I'm taking fenugreek and milk thistle, drinking mothers milk tea, taken two rounds of reglan and I'm lucky to pump 6 oz a day. Lo is 6 months old. Is it time to say goodbye to breastfeeding? I'm heartbroken