I can't produce enough breast milk. Should I consider infant formula?

No. Your body produces as much as your baby needs so put him more often to your breast. Instead of giving your baby formula, drink some nursing tea or even beer (I know it sounds strange but it helps producing more milk and it doesn't affect your baby). If you include formula in your baby's menu, you have more chances to lose your milk completely because for a baby is easier to drink from bottle then work on your breast :)