I am in a relationship with a an HIV positive person, what can be done to minimize the risk?

I am in a relationship with a an HIV positive person, we use protection all the time, we also do oral sex and that’s my worry, what are the chances of getting infected throw oral sex?

What can be done to minimize the risk?
I also want to know about kissing, we kiss a lot, that was before we found out about his positive status, and my negative one, can we gave a normal relationship without exposing myself to the virus?