Breast milk AND formula?

So with my first, I physically couldn’t breastfeed. I have like F sized breasts and it was just impossible. I pumped for a couple weeks but then found out my baby needed to be on soy. So going into my 2nd baby - I would love to pump and give her breast milk as long as I can, and hopefully she won’t have a sensitivity like my son did - but idk if I’ll be able to commit to solely pumping breast milk. Is it okay to pump what I can when I can... and give her formula other times?