Anything is possible, as it only takes one viable sperm making it to the egg!!
As far as if you are prego or not, it depends on when you O'd. And if sperm are in there they can live up to 5 days (from what I have read) so even if you weren't o'ing that day, it would be possible to o a few days later and get pg. If you were on day 10 or 11 of your cycle that would have you o'ing in time.......
but who knows!

As far as testing goes, I was 12 days past o when I got my faint bpf. But everyone is different and some take longer, some are quicker.
I would wait till 10 or 11 days, before trying to test. I tried the dollar store test and fot a bfn, but with an ept got my bfp. (Same day)
Best of luck to you!!!
Are you hoping you are, or were you done?