My baby is 10 days old and does the exact same thing. She sometimes throws up though.
My baby was the same from about 10 days old. I was so panicked and mentioned it to the HV. She said that while it's not really ideal because their tummies are so small, as long as she wasn't throwing up I should follow my baby's cues. Especially because they always say to feed breastfed babies on demand and there's no knowing how much they're actually taking so they could actually be taking in as much or more than they say the "limit" is for formula
My little one has similar pattern and amount. I rekon if was too much, he wouldn't take it and would bring it back.