I have been on PrEP for close to a year. A week ago, I sucked a person two times, they came in my mouth, and I swallowed twice. Now I'm super anxious, even though I'm on PrEP. What if I get infected?
I can understand that the first time you allow a man's cum inside your body, even orally, can be a moment of great fear. We have been told for more than 35 years to be afraid of men's semen, as it has been akin to disease and death in most public health messages globally.
Unfortunately, those (usually) well-intentioned messages fail to let us know that not all exposures to semen in all parts of the body carry equal risk. Oral sex, with or without pre-exposure prophylaxis (PrEP), is considered to be "little to no risk". With reasonable dental hygiene (i.e., no open blood sores), it is extremely unlikely to impossible for one to acquire HIV from swallowing semen.
At the same time, you share that you have been using PrEP for almost a year. Consistent use of PrEP offers more than 99% protection from detectable HIV if one is exposed. The reason we even know how well PrEP works is thanks to the volunteers who participated in the first four major efficacy trials, titled iPrEx, Partners PrEP, PROUD, and Ipergay. In all of these trials, some participants were given PrEP, and some were given placebo (or no drug at all).
The results: There were a significant number of new HIV transmissions among the participants who were not given the drug, especially those who reported receptive anal or vaginal sex. There were also a significant number of new HIV transmissions among the participants who were given the drug but did not take it as directed. But among the participants who were given the drug, had receptive anal or vaginal sex with partners whose HIV was detectable, and took the drug as prescribed? Zero new seroconversions. These data tell a lot about PrEP's ability to protect the body when exposed to detectable HIV.
It is very common for people to still feel anxious after starting PrEP. Again, 35+ years of fear mongering doesn't go away overnight. But if you are willing to have these experiences, and allow science to guide your decisions, you will find in time that anxiety will start to dissipate.
To answer your last question: If someday, somehow, you acquired HIV, that would not be the end of the world either. People diagnosed with HIV today, if they have access to medical care, do not have a life expectancy significantly less than people not living with HIV. With today's treatment regimens, people with HIV are usually able to get their viral load down to undetectable in a relatively short period of time. And once someone's viral load is adequately suppressed, they are no longer able to sexually transmit HIV to others.
It's unlikely that any of this is going to feel like much comfort until you get your next HIV test and see for yourself that the results are negative. You may need to go through this a few times before your mind can truly grasp the medical reality of how well PrEP works. But once it does, I hope you are able to relax and experience all the joys of connecting with others without fear.