So, you are right. A one time condom break IS low risk. A risk, none the less. Sincerely doubt you got HIV from that. And your flu symptoms are not HIV related. People don't get flu symptoms a couple of days after sex because of HIV. Symptoms are not used to diagnose HIV. The other risk you mention is a NON risk. The only ways people get HIV is from unprotected vaginal or anal sex or sharing of IV drug needles. The virus is inactivated by air and saliva. You can test at 28 days with a DUO test for the low risk of a broken condom one time.
4th generation antibody and antigen test at 28 days is a pretty good indicator on what is your current status. Although some people like to go with CDC guidelines (90 days)
28 days post the condom break failure will give you a clear indication of your HIV status. Protected sex is no risk.