Welcome to our Forum.  Thanks for your questions. The encounter you describe was virtually no risk for HIV.  Your partner stated that she is negative and get's tested regularly and indeed, most commercial sex workers do not have HIV.  In addition even if she had untreated HIV infection, far fewer than 1% of unprotected anal sex acts with HIV infected persons lead to infection and your case, you used a condom which virtually eliminates any risk which might have been present. That the condom slipped down a little does not change this.  If you had come to my clinic asking for PEP, I would not have prescribed it.---