Low supply?

Ti

My six week old baby is EBF, producing around 6 wet diapers a day and seems to be gaining weight fine, but I'm concerned my supply is starting to drop. When he eats from a bottle, he consumes about 4.5 oz, but I'm only pumping 3.5 to 4 oz. I never pull him off the breast and feed him on demand. He eats about every 3 hours. Does this mean I'm not producing enough?