Food supplement for formula

My baby is not even 11 weeks old and he's already on 8 ounces of formula. I'm basically upping an ounze every two weeks because he keeps asking me more and more! When I up an ounce he asks me for food every 3 hours, after a week of getting used to the new amount he asks me for food every 2 or 2 hours nad a half! I feel like he is not getting enough to keep him filled even though he is now on 8 ounces. I know we cannot give him cereals from 4 months old/ 6 months recommended but... I feel like this boy will get to a point where he is constantly feeding! Is anyone in a similar situation with their LO and have been recommended anything to include in their bottles?