Unprotected sex carries a risk for hiv. Depending on the specific circumstances of the episode, the risk factor varies. Given that it was a one time, brief encounter, the odds are in your favour that you are negative.
It is unimportant to your risk whether you ejaculated or not.
You should test at three months, and use condoms every single time with people of unknown or positive status.
Yes, a risk, but not a high one.