This incident was some time back. I rub my penis between the breasts of a woman and ejaculated using my hand some time later.

If there was semen from someone else on her breasts , is there a risk of me catching hiv or another std?

Many thanks 

Welcome to our Forum and thanks for your question.  Your rubbing your penis between your partner's breasts is a form of masturbation and there are no STI's including HIV which are transmitted through masturbation.  Further, STIs are not transmitted from person to person on a person's hands so, even if you had some of your partner's genital secretions (or another person's genital secretions such as would come from a prior client), there is no risk for acquisition of any STI.  There is no reason for concern and no reason for testing related to the events that you are describing.  

I hope that this information is helpful  Please don't worry. EWH

Thanks 

Correct, I see no need for any sort of testing at all based on your description.  

I hope this helps.  Take care. EWH