What are the chances of me being HIV positive?

I know that nobody on here is likely to give me a definite answer for that. I was tested 35 days after my last possible exposure and the result was negative, I've heard that a lot of people have detectable antibodies after 30 days, but the window period is set at 3 months in the UK. I'm in the most unimaginable possible state of mind. I haven't had any of the symptoms described on the internet, a bit of back pain, which I put down to anxiety because that's what I usually link it to, loss of appetite, but we're in the midst of a heat-wave. So I'm not really sure. The person who I might have contracted it from is not being very specific or helpful, one minute he's saying he's waiting for results, now he's saying they've found 'big traces' of HIV in his blood. I'm confused to hell. I really don't want any judgement on this matter either, because it's so painful. The local hospital rang the other day to say that someone had tested positive for something, but they can't say who (understandably) or what the infection is. Surely if it was HIV then I would have a right to know what may be happening in my own body? I don't know if this ex of mine is trying to wind me up, because (again, no judgement please) I was treated for a minor infection after my initial first test. If anybody could contribute their information, knowledge and personal experiences, I would be sincerely grateful.