Some babies do put that much away at 9 weeks, some are still only taking 3-4oz, every baby is different!
If your baby is gaining weight well and sticking to her curve, has plenty of wet/ dirty nappies, is alert when awake and content between feeds she is taking exactly what she needs! Make sure there is always a bit more in the bottle than you think she will take so that she can stop because she is full and not just becasue the bottle is empty and if she starts draining bottles add another oz.
Sounds like you are both doing great!
Laura