Hooray! I'm so glad Piffy is feeling better. I hope he continues to be healthy.
Have you tried sexing him? When I got Phoebe Mae, I was told she was a boy but I looked up how to sex bunnies before I went to get her and could see she was a girl. Turns out I was right. She was 8 weeks old at the time. In any case, you'll figure it out if he grows testicles in a couple months!