sexing guinea pig

I apologize my kid was helping with photos. Each picture is different guinea. Pushed in belly down and not penis shaft besides what is showing popped.

Hello! We have four sweet little 2-weekers who we are trying to sex so we can prepare to separate. Dad is now fixed. Mom is not. We have been trying to sex them ourselves but would LOVE some more expert opinions since we are new GP owners. Please let me know if I should provide any more photos...