Welcome to the STD forum.
Of course nobody can say that unprotected vaginal sex with a new and casual partner is zero risk, and I would encourage you to get in the condom habit if and when this comes up in the future. But the risk is low.
STD prevalence is strongly age-dependent, and relatively few women age 40 and up are infected with bacterial STDs (gonorrhea, chlamydia, syphilis, or the agents that cause nongonococcal urethritis), and the rate of transmissible viral STDs (HSV-2, HPV, hepatitis B virus, HIV) also is lower than in younger women. Even if your partner had HBV or HIV, the vaginal sex transmission risk is on the order of once for every couple of thousand exposures.
As for the bacterial STDs, most experts would not have prescribed antibiotics in this situation. But they will do no harm and certainly eliminated any risk of gonorrhea, chlamydia, NGU, and syphilis; one or the other drug is highly active against all 3 of them.
So my advice -- which would be the same if you had come to my STD clinic -- is that absence of symptoms so far indeed is reassuring, and that you have no worries and don't need testing for any STD on account of this event. Of course there is no absolute prevention against HPV or herpes, so keep on the lookout for symptoms (warts, genital blisters/sores), but both are very unlikely.
I hope this helps. Best wishes -- and try to stay saf(er) in the future! HHH, MD
Thank you for the explanation. I will heed your advice for any future encounters. I've read 4 to 10 days for herpes symptoms to present. Do you know what percentage of people present after 2 weeks? I would really like to start feeling better about this as the clock keeps ticking. Hopefully, I won't have to "keep a lookout" forever.
Thanks and last post from me on this subject.
Probably only around 10% of people with symptoms of new herpes develop those symptoms later than 10 days and it's quite rare later than 2 weeks. The risk you caught herpes is 1 in many thousand, tops. This should not be playing on your mind.