Welcome to the forum. Thanks for your question.
Although I haven't reviewed the data recently, I believe it has been many years since there was a case of HIV acquired by blood transfusion in the US. (You don't say where you are, but the same is likely true for all industrialized countries and maybe even world wide.) The blood screening system is highly effective in preventing HIV-contaminated blood, or blood products, from being used for transfusion. Further, any and all the standard HIV tests accurately detect all infections by 10 weeks, so you can rely 100% on your negative test results.
So the answer to both your questions is "zero". I haven't a clue what result might have come up on your immigration medical exam, but you can be sure you don't have HIV.
I hope this has helped. Best wishes-- HHH, MD