Welcome to the forum. Thanks for your question.
It would seem your online searching has led you to some inaccurate information -- or perhaps in your anxiety, you are being selectively drawn to information that increases your fears and missing the reassuring bits. The fact is that oral sex is safe sex. It isn't completely free of STD risk, but the risk is zero or very close to it for some STDs (HIV, hepatitis, HPV, HSV-2) and low risk for others (gonorrhea, NGU, HSV-1, syphilis). Below is the link to a thread that discusses oral sex risks in detail; please read it.
http://www.medhelp.org/posts/STDs/receiving-oral-sex/show/1524123
On the basis of a single exposure like you had, I don't recommend testing for STDs in the absence of symptoms like urethral discharge or penile sores. If nothing like this develops in the next couple of weeks, you can consider yourself home free. However, if you decide you must be tested for reassurance, you can have a urine test for gonorrhea and chlamydia at any time; and a blood test for HIV and syphilis after a few weeks.
Really, this shouldn't be a source of serious worry. Read the other thread as well, then let me know if anything isn't clear.
Best wishes-- HHH, MD