Well, at 5 months, you should see something down there. I don’t know what you know about bunny family jewels, but they are sometimes hard to see. They are raise pink areas about the size of the pad of your thumb and they are located in front of the genital area, unlike a cat or a dog where they are behind. Sometimes they can be a bit inconspicuous under the fur since they are on the abdomen like that. So take a look. But also keep in mind that absence of testicles does not guarantee a girl. Their presence, on the other hand, makes it pretty definitive that it’s a boy.

I don’t have any advice for you but I wanted to say that we were pretty convinced Bramble was a girl until he was about 4 months old and even then the vet wasn’t entirely sure he was a boy but thought he could feel testicles (they were not visible at that point) he had to wait till he was a little over five months old to be neutered because that’s when his testicles had descended enough it really is hard to tell with bunnies sometimes. Could you maybe see if you can feel testicles? that’s what the vet did with Bramble when we first took him.

http://www.rabbitnetwork.org/articles/sexing.shtml

Click on the boy and girl links for some pics. Honestly, you don’t need to try to make a penis pop out — round hole is a boy and a slit “hole” is a girl.