Making enough milk?

Christina 🐘 • 22 year old college student, married 4 years, aspiring proverbs 31, opera loving, unique, literary, soon to be teacher.
I used to not worry about my supply until lately when my 3 week old seems hungry and unsatisfied at most feedings. I've been pumping regularly now to feed her due to sore nipples. I pump about 3 ounces on average each time. I pump when she's feeding on the bottle. But when she feeds off the bottle sometimes she'll drink 4 or even 5 ounces! I have extra milk from my night pumping because I supplement a feeding with formula. What should I do? I feel like I'm slowly losing the race with bfing.