Fenugreek for milk supply

My daughter's pediatrician told me to try fenugreek to up my supply. I've been taking it for a little over a week now. I still haven't noticed a change. 😕 I'm supposed to go back to work next week and worried about her not having enough milk. I'm also worried that her pediatrician will have me put her on formula because she's not a huge baby. What are your experiences with fenugreek? Should I try something else?