Boy or Girl?

I have four baby rabbits, born just over 6 months ago. Two I know for sure are girls and one is for sure a boy. The fourth, Pink, I'd thought was a boy, but he's always been so much smaller than the one I know for sure is a boy, he's about the size of the two girls. He won't let me flip him upside down, so I lifted him in the air and felt for testicles....I didn't really feel anything, but he kept kicking me and his nails hurt a lot. The one I know for sure IS a boy, his testicles are big enough to be seen without having to grope him. How do I determine if Pink is a boy or a girl? He won't sit still long enough to get a good look.

Burrito him and check him properly. Boys can suck their testicles into their body.
How did you determine the girls are for sure girls? Did you examine for vulva vs penis?

Im hoping you have them all seperate.

Yes, the girls have no penises. They are together and get along amazingly. No biting, no trying to hump the other, just lots of licking and grooming. They're good sisters and they love each other and would probably cry[or do the rabbit version of crying] if I tried to separate them. The boy and this one are separate, but this one has a play area next to his mom's because he's a momma's boy and the other boy has a play area next to his sisters so he can see them, and those three are really good being next to each other. An occasional nose sniff and that's about it. I would have the sisters still with their mom, but she got sooo mad at them trying to nurse at 16 weeks, she finally started biting them and I had to separate her from them. I'll check Pink tomorrow, I just shut the door of the bunny room for the night and don't want to go bother them, they're supposed to be sleeping, or at least calming down and being quiet.

Please seperate them more then that. You need a gap between cages and play areas. If they can sniff each other then the boys can get the girls pregnant.