I remember reading something in men's health that sheds a bit of light on the whole thing. As adolescents we try to cum fast when jerking off cause we don't want anyone walking in on us as a result you probably don't have practice at lasting longer. When you're wrestling your snake get to the point where if you go any further you won't be able to stop, find this point and then like the other person said, stop and wait till it subsides, then work to that point again, it's like practice, do it a few times before cumming. Wait till your folks are really out of the house lol.

Next time your with her and she's giving you hand jobs and head for awhile, please her afterwards before having sex, it'll give you time to let the little guy rest up for the main event. And if you cum to fast and she's not really getting off help her after sex with your hands or tongue, don't just roll over and fall asleep. Too bad you're too young to buy a vibrator, maybe you could online or something. and use that on her.