The risk of contracting HIV from vaginal intercourse with an HIV+ woman is 0.04 percent per act. That translates to a 99.96% chance of NOT getting it. Even if you had unprotected intercourse with her 20 times, that works out to an 0.8% chance - of 99.2% of not getting HIV.
The odds of her being HIV+ are also very low, given that most people do not have HIV. If you use compound statistics (odds that she is HIV+ combined with odds that you got HIV from vaginal intercourse), the odds against you getting HIV from this event are extremely low.
Well, gonorrhea is far more common than HIV, for one.
Did you do testing to see if it's gonorrhea or chlamydia? Or something else?
Discharge is common with gonorrhea, but can also happen with other infections. Chlamydia, gonorrhoea, trichomonas and Mycoplasma genitalium can all cause discharge, as well as prostatitis, balanitis, urinary tract infections, and urethritis, which can have a number of causes.
Less than 1% of the world's population has HIV, and it's harder for men to get that from women than the other way around.
All you can do now is test, and find out what's going on. You can do a 4th generation DUO HIV test at 28 days and get a conclusive test. I'd be surprised if it's positive, even if you have another STD.