My 3 month old wont eat more than 3 ozs at a time & acts hungry every 2 hrs. how do i get him to eat more at a time & go longer between feeds?

Slowly increase: Slowly increase the time interval between feedings, for example each week go upby 10-15 minutes. If the baby is feeding at 2 hr intervals go to 2hrs and 10 min week one then two hours and 20min week two. As the time increases the amount of volume should increase also. Good luck.

Don't force it: Eating 3 oz every 2 hours is pretty good for this age. Dont force it. There is no guarantee feeding them more will space out the time between feeds. This will happen naturally as the child gets older. The most important thing is that the child is gaining weight appropriately.