Dear Dylan, okay you will need to act fast. If you are being for real about this you need to take her to the hospital under privacy. If you shot in her time after time there may not be a chance. - Dr. clay Ellis
You should be concerned and might want to use the day after pill to prevent the sperm from reaching an egg. However, the risk is lowest after the period for many women. Just on the odds it's very slim. A good idea would have been to go to the drug store and purchase spermicide to flush with, probably too late now. I would have her contact her doctor just to be on the safe side as said above asap. She probably can still take a pill to prevent pregnancy. I think it takes a short time before the sperm makes it way there giving you a small window of time to still block conception even if there is a slim chance of an egg. Most women won't be able to conceive on day 1 however I know a woman who did. So yes it can still happen even though very rare.
Risk = low
But don't chance it.
Just looked this up. Anywhere from 45 minutes to 3 days for the sperm to swim. The odds are in your favor she was not ready to conceive. But act fast!