Oral sex is not a risk for HIV for the reasons that Ruby already explained. But oral sex CAN BE a risk for OTHER STD's, which is the reason why Ruby recommended that someone like you who engages in oral sex on a regular basis makes sure to test for those other potential STD's. It's the responsible thing to do for your health to test regularly.
The HIV window period for testing does not apply to your situation because oral sex is not a risk for HIV.
Regardless, the experts who used to post here always said that 3 months post exposure is conclusive for all generations of test currently on the market. The 6 month window period has been outdated since 2004. And the 4th generation duo has been said by many experts to be conclusive at 28 days past exposure. Anyone who still clings to the 6 month data is in desperate need of updating their knowledge of HIV testing because they are living in the past.
Oral sex, even with a sore throat, is not a risk for HIV. There are enzymes and bacteria in human saliva which renders the virus inactive. (Unable to infect)
Oral sex CAN transmit other STD's and you may want to test for those. It is recommended that anyone who engages in oral sex be checked every three months for infections.