Welcome to the forum. Thanks for your question.
Congratulations on a smart approach to sexual safety. You were right to insist on a condom and I'm glad you were assertive about it. Many women are not!
In general, African Americans have substantially higher rates of HIV than other racial/ethnic groups in the US. That doesn't mean most black men are infected, but it does warrant an extra measure of caution. The reasons are not because of promiscuity; most AAs in the US have no more sex partners than whites, Asian Americans, Latinos, etc. Below are links to a couple of threads that address this issue.
http://www.medhelp.org/posts/show/717093
http://www.medhelp.org/posts/show/1261996
To your specific questions:
1) The notion of microscopic holes or leaks in condoms is an urban myth. When a condom breaks, it splits wide open. If the semen was contained, protection was complete.
2) Condoms work. For HIV prevention, their success depends on containing semen and having the head of the penis and urethral opening covered. Coverage of only half the penile shaft is quite common and although this may somewhat elevate the risk of herpes, HPV, and other skin-to-skin infections, protection against HIV, gonorrhea and chlamydia isn't affected. The symptoms you describe are typical for anxiety, not HIV; they don't concern me.
3) The problem here is the difference between your objective, intellectual analysis (no measurable risk of HIV) and your subjective side. Call it left brain versus right brain, if you wish. I recommend you be tested; until you have a negative test result, I predict you'll continue to wonder and worry, despite any reassurance I can give. When you test, you definitely can expect a negative result.
In the meantime, if I were in your situation -- or if I were advising my daughter or anyone close to me -- I would not advise holding off on sex with any regular partner you may have. It is exceedingly unlikely you caught HIV during this exposure.
I hope this has helped. Best wishes-- HHH, MD