Did you get any STD testing? It's possible to get gonorrhea and chlamydia from oral sex. You'd need specific tests for those. It's a good sign that you don't have any WBC in your urine, but you should still get tested.
In the meantime, maybe you just need to increase your water, and decrease your caffeine/alcohol/carbonated drinks/juices? Those are very irritating to the bladder.
As AJ said, you can get gonorrhea and chlamydia via oral sex. It's not common but it can happen.
3 weeks is more than enough time to get a good reliable test. Statistically it's unlikely but it's worth getting peace of mind.
Anxiety can feel symptoms especially altered sensation as you've mentioned lack of discharge (though alot of people do not get any symptoms at all).
Try drinking more water and get a test done, if the problem still persist see a doctor as it could be something like prostatitis or nsu which is caused by anything.