Is it still beneficial?

Is giving your baby breast milk AND formula still beneficial? I wanted to strictly breastfeed but I have to pump and I’m not pumping much. Ill get one ounce from pumping both breast and two ounces combined.. I pump every 2-3 hours but it’s not enough to store in a bag.. I still give it to her but if she’s still hungry I give her formula. Breast milk is so natural and healthy for her I didn’t want to give her formula but I’m not producing much breast milk. I don’t breastfeed because she isn’t latching and I’ve tried multiple times. Even talked to a lactation consultant three times. I’ve also tried a nipple shield she just doesn’t stay on long.