If your period is late now, you can take a pregnancy test.
If not, then you'll have to wait until either it is late or 'til it's been 10-14 days since the incident in question, whichever is sooner.
A test is going to be much, much more reliable than looking for "signs".
Basically, you do have a potential pregnancy risk any time there's direct contact between your genitals and his. So in future, it's a smart idea to get a condom on him as soon as he's got an erection, before you start the rolling around, okay?
Direct genital contact also creates a risk for STD transmission, so both of you need to think about getting screened.
[This message has been edited by logic_grrl (edited 07-05-2003).]