Well done cowie!!!
I'm not sure which is which right now but I know that there are 2 hole's on the under side, for 1 sex, the holes should be far apart and the other sex the holes should be close to each other, I hope this makes sense.
I had this trouble when my hamster gave birth to 12, but luckly I got it right (well there were no more babies so I must have,lol).
Ky and Rio