Yes that is quite possible. There would have been residual semen in his urethra and that could have made its way into your vagina. That is apart from his pre-cum which would have mixed with the residual semen.
Peeing would flush the urethra, but some UK research has indicated that some men always have sperm in their pre-cum.
It need only take seconds for the sperm to swim in.
I hope this helps.
Well you could possibly become pregnant in due time. That takes a few days. You could of course take EC if you felt that were appropriate. That has to be taken within 3 or 5 days (depending on the EC make) of intercourse - where do you live?
If you want to wait to test it is best left until your period has failed to arrive (if you are regular) + 2 days otherwise 21 days from date of intercourse.