Thanks for your question.  I think many people are surprised by just how hard it is to get infected through oral contact. This is true not only for STIs but for all infections.  Interestingly enough there are more bacteria present in the mouth than anywhere else in the body (even the rectum) and we are constantly putting things into our mouth hat could cause infection.  Whatever the reason, the mouth is a hard place to get infected and ingestion is a difficult way to become infected.  Thus placing another person's breast I your mouth, even if they are lactating or have discharge cannot cause infection.  No one has ever been documented to be infected with HIV or hepatitis in this way.  The same is true for other common STIs.  The only exception to this statement would be if a person had an active syphilitic or herpes sore on their breast and that breast was vigorously place in contact with another person's mouth,  This however is very, very rare and simply not a meaningful concern.

Thus, for the exposure you describe, there is no reason for concern, and no medical reason for testing whatsoever.  I hope this information is helpful to you.  EWH