spend a long time giving her oral orgasms, also getting your fingers right up her and finding the little I win button
When your fucking as soon as you even remotely think your gonna shoot your load switch positions, try insert oral between switches if you really struggle.
And as said before KEGELS FTW! once you start doing them you can pull out and do a full body tense focused around your pelvic muscles and this usually helps the sensation from subsiding, once you get really good, you can orgasm without ejaculating, ive managed to do this three times once, while practising it solo, and it was by far the best experience or orgasm ive had, ever, was literally laughing with joy afterwards.
Another trick is your nuts tend to retract up into your nutsack/body before you unleash your population paste, a cheeky method is to GENTLY handle them and pull them back out to there normal position.