1) You can have a test at 4 weeks, if it is an 4th gen DUO TEST (P24 and antibodies). it would give you a 95% accuracy, then at 6 weeks and finally at 12 weeks, some guidelines say 6 weeks is conclusive, other say 12... it's up to you. but... if you want some reassuring, some say that a duo test at 18-22 days it's a good indicator of posible outcome(70-80% accuracy). you can take it there for keeping your nerves calmed, altough it's not conclusive
2)Your symptoms doesn't ressemble ARS at all, and even so. HIV can not be diagnosed with symptomps, you have to get tested. Next time, if you think you were at big risk of getting HIV, ( because you live in a place or region of high risk population, or something else), you can seek for PEP at an emergency room of a hospital, if you are within 72 hours post exposure. the the best recommedation is between 2 to 24 hours.
3) for vaginal sex is 1 out to 2500, according CDC guidelines, so its considered a medium risk compared to anal sex. source: https://www.cdc.gov/hiv/risk/estimates/riskbehaviors.html
Agree to test at 28 days with a Duo 4th generation test for accurate and final result. PEP is NOT necessary for most one time exposures. Especially with a coworker that is most likely not HIV positive and a low risk partner.