Am I running dry.. Already?!

So last week my refrigerator had four 6 oz storage containers of milk & two 10 oz containers full at all times. This week I can barely pump out 3 oz every couple of hours. My baby is only 3 weeks old. I don’t remember this happening last time around, & I ended up breastfeeding for 2.5 years. Am I losing my milk? And if so, is because I’m doing something wrong? It kind of makes me sad 😔