I'm thinking you should not have started pep from what you describe and a doctor was irresponsible to give this to you. That is usually reserved for having unprotected sex with someone KNOWN to be HIV +. She was concerned you wore the condom, you had the condom and she confirmed it was on. So, you are having anxious thoughts. Stop taking PEP. It's not warranted in this situation and can have a lot of side effects. You can't get HIV from protected sex. The only risks for HIV are having unprotected vaginal or anal sex or sharing IV drug needles. Only the head of your penis needs to be covered. You are imagining no condom due to anxiety. If you have an issue with anxiety, then test at 28 days but you don't need to. A one time exposure, worst case scenario is LOW risk, less than ONE percent. I'd also like to comment that perhaps you should rethink the drinking. If you find yourself not able to really recall things or aren't in control of yourself, that is drinking too much. But in this case, you didn't need pep and I'd not worry about HIV.
1 You started sex using a condom but think you took it off after awhile?
2 Did she supply the protection? I'm not sure why you think she would allow you to take the condom off after you started.