It's possible that you're just beginning to see/experience symptoms, yes.
Chlamydia is considered "silent", meaning many people infected will not present or notice any symptoms. If symptoms do occur, they are usually experienced within 7-10 days after exposure. If a person becomes infected, a test for chlamydia (as well as gonorrhea) will likely come back positive within 1-2 days.
NGU is caused by chlamydia. So, whoever had chlamydia technically gave you NGU. Honestly though, the "who done its" in this situation shouldn't be of importance. Again - because the disease is silent in most, it's difficult to say who acquired it first and who passed it to whom first.
What's IS important here? If all three of you engaged in unprotected sex, have a standard STD/STI panel performed to rule out anything other than chlamydia, and get treated with antibiotics asap. Finish your course of antibiotics before having sex again, unless your doctor specifies otherwise.
Best of luck!
Did the friend actually show you her results?