Yes, you have nothing to worry about !
Practically, ORAL SEX IS NO RISK.
Move on !
oral is v v v v v low risk (or almost 0) to start with, your guy was probably neg anyways, and now you have a 5 wk neg. maybe your convinced cos of some other factor. take another test in a few weeks for your peace of mind.
you really think I have nothing to worry about?
I have no idea, you tell us.