Breast milk reducing in amount

I had my child 3 weeks ago and my supply took a few days to come in but when it did it was a good amount but the last few days it’s reduced. I was able to pump about 65 ml from both breasts everytime I pumped sometimes even more. But now I’m pumping less about 30ml or so. I’m nervous that I’m drying up. I had my baby shower Saturday and was out from 8 in the morning until 8 at night and I wasn’t able to pump because I was just so busy and had no electrical source as my shower was outside. Could that have cause me to lose my supply?