On 9/18, I received oral sex from a female. She was tested on 9/26 and I was tested on 9/30. I tested negative for chlamydia, gonorrhea, and syphilis and she tested positive for chlamydia. I have no symptoms re: discharge or pain during urination. How confident can I be in my results or would you recommend additional testing for me for anything? 

Welcome to the Forum.  short answer is that you are in the clear.  Your negative tests, like her's provide evidence that no STI was present in either of you.  No need for concern or for further testing.  You can move forward without concern.  EWH
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Her test results for chlamydia were positive, though. Can I still be confident in my results?

Yes, not all exposures lead to infection. You tests prove that you were not infected.  Chlamydia is very rarely acquired from receipt of oral see.  EWH---