my Belle also drinks similac, she's 4mths old now, and she is drinking 140ml per feed. But we go according to the indicated amount on the tin can ie 2 spoons + 1/3 spoon of milk powder for 140ml feed.
As to how much one baby should drink, it really depends on individual's appetitie ( i tink since i am a 1st mom ) if your boy seems satisfied and happy after the feed and doesn't cry for more, should be alrite
any reason why your pediatrician ask you dont't see the indication on the tin can??