The female g spot is only like 3 inches in I believe. And here's a little tip for anyone who doesn't already know how to do it. While she's on her back

use this hand motion and repeatedly trigger your two middle fingers like your shooting a semi automatic. This can even get so rough that you don't have to move your fingers anymore you can just pull your entire hand up and down. It's pretty common but I didn't know it when I was younger. Game changer and works every time like clockwork but you gotta get the technique down. Sorry if that's too much info for anyone but for anyone who needs it, your welcome my friends