you may want to try extending A time during the morning and pm. my lo is 9 months also and stays up 2 1/2 to 3 hrs in the am before her nap, and definately 3hrs in the pm before her nap. if you are going to extend A times though do it gradually 15 min at a time every few days - to find a happy medium for your lo.
i would still offer a feeding before 'lunch' even if he doesn't want to take it all imho.