Welcome to the Forum. Your lingering questions suggest that your anxiety is continuing to get the best of you. Your possible scenario is something that is incredibly unlikely and has never been described. The possibility of of an animal bite/"nip" transmitting HIV has never been reported. The idea that a dog might get HIV infected blood or secretions in their mouth and then Transmit it to you is simply unrealistic and should not concern you.
As far as the concern about "rare strains" are concerned, these strains are rare both in the parts of Africa where they are seen and rarer still (in fact vanishingly rare) in North America. I urge you not to worry that your tests might have missed such an infection should not be a concern.
I hope my comments are helpful to you. Please do not worry about the possibility of having gotten HIV from any of the scenarios you describe. EWH
These are unrealistic, non-medical concerns. My sincere advice is that rather than asking questions of HIV and medical specialists to discuss these concerns that you know are unrealistic with a mental health professional. I say this out of concern. Nothing more to say. EWH
Many thanks Dr for your quick response and your patience. I know I'm not supposed to worry about incidents aside from sex and injection by needle, but I feel some events are very risky and can't understand why. One other 'possible' exposure banging around in my mind was I shared a room with a friend who talked about dating a guy, and she later suspected he was bisexual. After hearing that I worried about anytime there could have been menstrual blood on the toilet and I got blood on my fingers, I could have passed it to my vaginal/anal area,if I scratched myself. Because I have dry skin I worried I scratched myself in the vaginal/anal area more than a usual person, and its possible my finger could have poked inside me, transferring blood to inside my vagina or anal area. I just feel like its very risky, especially if I got a lot of blood on my finger, but I know I'm not supposed to worry about these kinds of things.