Okay so I'm 16 and tried fingering yesterday for the third time. It normally starts to hurt so I stop but it didn't this time so I kept going and I got in about 3 inches. When I went a little further I could feel my pulse on my finger. I could feel it very well, is that normal? is there a main artery there? I quit after I felt it. Freaked me out
No worries. You are probably feeling your pulse through your inferior rectal artery. Totally normal. Happy exploring. (!)
There's a lot of blood vessels on the inside of the rectum. Like Imgay47 said you just managed to find one of the major arteries. If it hurts when you're doing it though you probably aren't adequately lubricating your fingers.
From having absolutely no experience with this wash your hands thoroughly first because little specks of dirt can make it hurt and what are you using for lube?