How much is too much?

My son is exactly 3 weeks today and I’m breastfeeding (pumping) he usually drinks 3 to 4 oz .. 5 if he’s really hungry but lately my milk has been low and my family members just put it all in one bottle and give it too him and expect me to be able to produce more when that’s all I had at the moment I pump every two hours, I drink mother’s milk tea also eat lactation cookies the last 2 weeks have been really hard for me and I’ve been doing all I can , but I also feel like he could be eating too much because he throws up here and there and after he has gas he cries I just want to make sure he’s getting enough while saving if I can I just hope this goes over and my milk supply comes back 😩