Welcome to the Forum.  I'll be pleased to comment.  Most commercial sex workers do not have STIs (including HIV), and most unprotected exposures to do result in infection.  Further, as a CSW, your partner probably takes precautions against infection, including regular check ups (as a professional, particularly a high end one, I would expect her to be particularly careful in this way- to do otherwise would be bad for business).  I would assume that the likelihood of her being infected is lower than the likelihood of infection in a casual partner picked up in a bar who might not be as likely to take the same precautions. In addition, while there are no studies on the matter, it is logical to assume that the longer an exposure the more likely transmission is to occur and therefore the short duration of your exposure is in your favor.  For these reasons, I judge your risk of infection to be quite low and personally would not be terribly worried.  On the other hand, low risk is not no risk.  Depending on your circumstances, you may wish to test for the most common STIs such as chlamydia and gonorrhea.  Alternatively, you may simply choose to watch carefully for symptoms (penile discharge or burning on urination).  If no symptoms develop in the next week to 10 days, I would put your likelihood of having been infected in the encounter you describe as being close to zero.

I hope this comment is helpful.  EWH