Could this be reflux?

My baby is nearly four weeks old and she has always spit up milk after feeds, wether that’s formula or breast milk.

It’s not sick, just milk coming back up. She is a hungry baby and is already on 4ounces. Even that isn’t enough and she needs boob after bottles.

Her spitting up milk is like a small teaspoon amount.

I’m a first time mum so I genuinely do not know much about babies I’m learning as she is growing.

My midwife said spitting up is normal and it’s because babies spit up what they don’t need in their stomach.

Im worried she could have reflux or something or could she be irritated by her milk?