Increasing Milk Supply

I am EBF and I noticed within the past week I can't seem to pump as much milk as before. My son is 14 weeks old and I work 4 days a week. I am completely stressed out because I can't seem to get enough pumped for a work day away from him. I eat well, drink water and as of yesterday I started taking fenugreek. I also am taking Brewers yeast pills. We have only supplemented a couple of times and ever time my son gets so gassy and miserable and he pukes the majority of it up. I just ordered some bars online that are supposed to help but I haven't gotten them yet. Are there any tricks you have that can help? I was also diagnosed with hyperthyroidism . I feel like the meds are affecting my milk supply so I stopped taking them yesterday.