Hi,
yes, unprotected sex with someone of unknown status is a risk for infection. However, having ars symptoms now is generally too late if you had the encounter in october. Unless you are undergoing chemotherapy, regularly taking iv drugs or any other factor to significantly reduce your immune system, then initial hiv symptoms occur 2 -6 weeks after the episode, or not at all. After that point, antibodies are detectable.
As far as your blood transfusion goes, yes they can detect hiv from an early stage. They would not welcome you back to donate more blood.
The only definite way to confirm your status is to have a test. At this point, it will be accurate and reliable. I am highly confident of a negative result. Especially after a single encounter (each unprotected encounter with a person who is hiv carries a risk of aprrox. 1%).
