My cat gave birth...

Our cat Wiz, just gave birth but the whole time we thought it was a boy. My brothers friends dropped off a kitten and told us it was a boy, I know you can tell really easy but we just never checked. We’ve never had a girl cat and she just got along so well with our two boy cats and they all acted like boys. But I came on to ask what we should do? We thought she was just fat cause my dad kept over feeding her, so we weren’t there for the birth but she had two kittens in my parents bed lmao. We are gonna take them to the vet on Monday but I just wanted to know what we should do?