Baby throws up only breast milk

Di

A little back story, my baby is 1 month old. She won't latch so I pump. Which I'm already upset about because I really wanted that bond of breastfeeding her, but I'm happy I can at least pump. Pumping can be a struggle since i don't always make much. My nipples are cracked and blistered and constantly feel like they are on fire, but I don't want to stop giving her breast milk. So since I don't always produce a lot of milk, I give her formula sometimes too. She barely ever spits up when she drinks formula. But when she drinks breast milk, she spits up little bits that equal about an ounce worth, and then sometimes she will projectile vomit it where it just pours out of her mouth and nose and soaks her. It kills me because A. I hate seeing her uncomfortable and B. I work so hard to give her that milk and to see it go to waste like that makes me so upset. I sit her up and burp her when she's done. If it was reflux, wouldn't she throw up the formula too? Maybe it's something I'm eating that's going in the breast milk that isn't agreeing with her but I have no idea what it could be. She also cries a lot after she eats breast milk but not formula. Maybe because it upsets her stomach? I don't want her to be uncomfortable or in pain but I just want to give her breast milk! It is so upsetting and frustrating. We see the pediatrician on Monday so I will ask him, but wondering if anyone had any experience with this. TIA!