The only risks for HIV in adults are:
1) Having unprotected (no condom) penetrative anal or vaginal sex, OR
2) Sharing IV drug equipment with other IV drug users.
If you don't do any of those activities with someone of unknown status, or of known HIV+ status, you will NEVER have to worry about HIV.
HIV is NOT transmitted by oral sex. No one has ever contracted HIV from receiving oral sex, whether it was protected or unprotected.
I can't help you with anxiety, but if it is affecting your life, you should consider seeing a counselor.