Help with the BC muscle.

Hey everyone, been a lurker for some time now but decided to get serious.

I’m having a bit of trouble finding my BC muscle. I’m easily able to identify it when stopping whilst urinating, but when I’m doing it whilst sitting down it’s practically impossible for me.

I’ve done some searching and reading but there’s still one thing I’m confused about. I ‘might’ have found it, but when I squeeze the very lower bit of my stomach goes in. Is this right? =/ Thanks everyone!

Here: Locating the bc muscle