Will giving my baby 1/2 oz of more formula allow longer streches til the following feeding? my baby normally eats every 3-4 hrs today its been every 2

Needs more: as your baby grows he / she needs more calories, so if asking for more that means he / she needs more, check with your pediatrician during the next visit on how much more according to actual/expected body weight

Good plan: You can always prepare a little extra, especially if the kid empties every bottle. If you work to have about 1/2 oz left after every feed, you will always stay just ahead of babies growing needs.That also helps you gradually increase the spacing.