Hi there, welcome to BW.
I cant be of much use here but i can completely relate to this. My LO or should be big one is exactly the same as yours, he was 9.11 at birth and he is now 10 weeks old and putting on weight at approx 1lb a week and is currently 17lb and 28 inches long - god only knows what our boys are going to be like when they are fully grown!!!!!!!
Ive just started to increase to 6oz even 7oz for his first feed of the day and he can only go around 2.5/3 hours if that, so any advice would certainly be great.
Tracey