With regards to HIV, you had zero risk. HIV is only transmitted in adults through vaginal or anal penetrating intercourse or sharing IV drug needles. Transmission takes place inside the body. HIV is fragile and deactivated by air and saliva. So, your activities were zero risk for HIV transmission. With regards to other std's, you had some minor risk. Receiving oral sex is minimal risk at most and would involve an issue of something like if she had oral herpes (cold sores) which is called herpes simplex 1. This could potentially transmit but is rare. Syphilis, chlamydia, HPV and gonorrhea are the others with small potential of transmission. Chlamydia is hardly ever transmitted from mouth to genitals. Gonorrhea is probably the biggest risk from receiving oral sex and that would likely result in discharge if you had it.
Again, frottage is no risk for HIV. Skin to skin contact is a way that some std's are transmitted such as herpes, syphilis, or hpv. Again, this is a low risk. Here is a thread by a MedHelp expert doctor regarding this where he states that in his over 4 decades of treating std's, while there was a theoretical risk, it never really happens. https://www.medhelp.org/posts/STDs/Likelyhood-of-STDs-from-frottage/show/1781688