I had sex for the first time on 8/15/12 near midnight, so let's say it was 8/16/12. I'm a guy, and my sex partner was an older woman. I won't say my age, but I am between the ages of 18 and 21. I received oral sex briefly from the woman without any protection , ejaculated, and received unprotected oral sex again, briefly. We then had PROTECTED sex immediately afterwards. The woman is somewhere between the age of 25 and 30 (I won't share her exact age), and I had known her for about 3 months before we had sex. It was a very unplanned sexual encounter, and I don't know much about her sex life. However, she has mentioned an ex-husband and an ex-boyfriend to me, so I'm know she is relatively sexually active. She also told me that she was tested in May or April and was did not test positive for any STDs, and told me that once she knew I was clean and tested, we could have unprotected sex.
I was very nervous about the situation, so I went to set up an appointment for an STI test the next day (the morning of 8/16/12). My appointment was set for 8/22/12, so I went in on that day to give my blood for an HIV test and urine for other STD tests. In retrospect, I only gave myself about 6 days in between to get tested, but I was very nervous. After some online reading, I have come to understand that my chances of getting an STI at this point are very slim, but I just want to make sure. I got back the results today, which gave me a clean bill of health. However, I want to be completely sure that this is the case: when should I get tested again to make sure I didn't catch anything? I feel some sort of tingling at the tip of my penis, but that might be because I have been urinating A LOT (I've been drinking over 15 cups of water per day (long story)). I also occasionally feel some testicular pain, but that sometimes happens when I get anxious and my stomach clenches (a mind state that I am currently in).
How should I go about this? I must be coming off as paranoid, but this was my first time so I'm pretty nervous.