I would honestly completely cut our all bottles for the next several weeks. feed baby whenever he is fussy. short frequent feeds are actually better for your supply. the first few days will be a little rough. but your supply will increase quickly. my 4 and a half month old still eat about every hour for about 10 minutes. and sometimes even longer just hang in there. your body will do what it's supposed to. good luck. and remember you are constantly making milk. so even if baby isn't getting a ton he will still be getting some.

The first few weeks are important for establishing a good milk supply.
You want to nurse your baby frequently. I would nurse every 2-4hrs and lasting about 20 minutes each side.
Make sure your baby completely empties out your breast. It's important they get that fatty milk in the end because it will keep them full and gaining weight.
Drink lots of water. Breast milk is mostly water so you want to make sure you're drinking plenty of it.
Eat well. Don't skip meals.
I wouldn't supplement with formula. It can make it hard to establish a good milk supply if you do. If you must then first nurse each side 10-15 minutes each and if after your baby is still showing hunger cues then go ahead and offer an ounce of formula.
It's hard to tell if you're making enough. If your baby nurses good and after is calm and sleepy and hands are relaxed then you're making enough.