Hello sir,
First let me agree with everything Dan said
Second let me commend you on doing a lot of things right - getting tested with a partner together, taking precautions with condoms with the friend with benefits. I think you should take time to acknowledge that you are doing the right thing on several levels!
Finally, I don't think you're risk is high at all. Oral sex is really extremely low risk, if not no risk at all. Of course the receiver is less at risk, but even the giver isn't at any risk, unless they have a large cut in their mouth and there's a good amount of precum or semen that gets in the open wound, from a partner who is hiv positive, and NOT on medications. In other words, a lot of conditions would have to be met for oral sex to be a risk at all. And can you imagine if HIV was easy to catch through oral sex? Almost everyone would have it if that was the case.... the vast majority of people do not use condoms or dental dams with oral sex, so just logically, one would have to understand that you have to do more than oral sex to put yourself at risk for HIV.
That said, oral sex can transmit gonorrhea, syphilis, warts and herpes - so don't think that you have no risk for everything because you just do oral sex. Get checked up regularly regardless, just a good idea - like getting your blood pressure, cholesterol and yearly physical exams done.
David