My cycle are usually 25 days. So ? ;(
I second all that advice and add that if it's been less than 72 hours you do have the option of getting plan B or another emergency contraception. This is a large amount of hormone and can have some side effect so it shouldn't be taken as a regular option (they suggest no more than 2x a year). However, if you're concerned about getting pregnant it's the only other active thing you can do. If it's been more than 72 hours, just try to wait patiently. The odds are in your favor for not being pregnant and stress can do horrible things to the body so for now, just wait and see. And in the future, just learn from this hiccup and take much better precautions. Personally I recommend doubling up on birth control - pills and condoms. Pills can fail and so can condoms, if you don't want a baby putting both barriers is the best way to avoid it.
It doesn't matter how long he was inside you for, or if he ejaculated or not - you can still get pregnant from this. Pre ejaculation is released just by him being aroused and this can contain sperms to get your pregnant.
That being said, the last day of your period is not usually your most fertile time - meaning that ovulation probably isn't for at least another week or so so chances are slim, but could still be possible if you have short cycles.
All you can do wait till your next period and if it doesn't show then take a pregnancy test. Maybe an idea to use condoms in future too.