It's not unusual for babies this age to eat every 1-2 hrs. They're getting plenty. The more you nurse and empty your breast, the more you'll make. I would definitely stop supplementing right now. This is only going to cause problems with your supply, not make it better. If you're still concerned about your supply and increasing it, then you can definitely pump.
The rule is the more you empty your breast, the more your supply will increase. Don't doubt yourself on this. It will get better

. I know it feels like they're eating all the time but this will help your supply in the long run.