Heterosexually acquired HIV is less common than you seem to think. Most women with heterosexually acquired HIV are the regular partners (i.e., multiple sexual exposures over months or years) of men with known HIV infection or at least at known high risk. You describe none of that. Therefore, the chance you have HIV is low. It is hard to put a number to it, but the statistics say that there is one chance of transmission for every 1000 episodes of unprotected vaginal sex, although it is higher for anal sex. That's if one's partner is infected--which, from your description, is unlikely.
It was smart to be tested for peace of mind. Every sexually active person (outside committed relationships) should be tested for HIV from time to time, like once a year. But it will be very surprising if your test is positive. I hope you also were tested for other common STDs, like gonorrhea and chlamydia. The chance you have one of those is way higher than the likelihood of HIV.
I hope this helps. Best wishes-- HHH, MD