Measuring the curve?

I am going to stick with the straight ruler to measure gains. What I meant was does anyone agree that measuring the curve with tape is more accurate to its actual length. If so, doesn’t that mean I am putting 6.5”NBP(tape) inside the vagina as opposed to 6.25”NBP(ruler). Also, I am using the ruler because that is what I have always done and I don’t want to switch it up at this point in my PE journey. I just think it would be cool to know I am filling her up just that little bit more.

Yes, it points up, not out and I cannot push down on it when erect. If I try to push it parallel to the floor, it feels like it will explode! Very painful.