I read online and saw that this could just possibly be Mono
This was your biggest mistake, trying to diagnose yourself online, God knows if its Mono, for all you know it could be a flu. Primary Infection in HIV comes all at once, you dont get sore muscles one week followed by a sore throat the next. You also dont get your lymph nodes on your neck swollen, you get a lot of lymphs swollen all at once, and even if you had this it could be a garden variety of things. Given that she is your partner and though she has had a few partners back, I am taking it you guys are monogomous, good. Its always a good idea to get tested before having unprotected sex in order to get some peace of mind. Your risk is low in that its only one partner, you know who she is, i am sure you have an idea of her trajectory. However, you guys are having unprotected sex and would be a good idea for you both to test not only for HIV but a complete std test. It would relieve your stress and would help you get on with your life.
Sorry this is not the drs forum, but unprotected sex does place yu at some risk, since you are worried the only way to know is getting tested, the symptoms are useless and meaningless sice they are way to common and only 50% of infected people got symptoms, and they probably got them from other virus rather than hiv.