Here are am couple of videos I uploaded onto YouTube a few years ago, it will show you how I pop ball pythons.
https://www.youtube.com/watch?v=E0qFgPYWmX8
https://www.youtube.com/watch?v=qUwCI_xjaIk
If you want to probe your snake check out this video.
https://www.youtube.com/watch?v=AzMhR3OZTKI
It looks like one of your thumbs needs to be a little further down the tail when you apply pressure. My guess is that it took me about 100 attempts at popping before I had a handle on the technique.
Yes it looks like scent glands, but that doesn't mean it's a female.
Does the person you bought the snake from know how to pop?
If the answer is yes then I would continue popping the snake until you see the peens.
If you have more questions feel free to call me at 408-981-6694, I'll help any way I can.
Good luck
Brian