They are a lot tougher than you think

When he popped her it looked to me to be very hard...so much that poop and pee squirted out with some force.
Far from unusual with younger individuals.

I recently popped her just to see if anything looked strange, and all I can notice is that when I pop her I can only get one white "nub" to pop out instead of two (the white nubs that femals have where a males hemipenes would be).
Seems to me that you do not apply enough pressure when popping.