reliability of a 4 week test?

[freaked_out_again]

As some of you may know I am having a difficult time with my "low risks"  To sum things up...I wrecked on a bike and scrapped my arm pretty good.  2 days go by and someone I know who has been rumored to have hiv ends up touching mu wound.  Now I am not 100% positive that this person did indeed touch it, but I though I felt a touch.  Ever since then I have been a wreck worrying that somehow this persons hiv  inflected blood came into contact with my wound. Because I have been such a mess, I ended up testing at 4 weeks, I know its early, but I HAD TO. Test came back negative.  I know I am going to end up testing again at the 3 month mark, but I just really need to know how encouraging 4 weeks negative is.  I even have had an incident at the post office where I smashed my finger and began to bleed thinking someone elses blood may have came into contact with mine at this public place...I know I need help, but I keeping running the worst case scenario through my head (infected blood contacting my wound...) If blood did indeed touch my wound, how much of it would be needed to cause infection? a tiny drop? Half a tiny drop? a liter?  Please, I really need to know how much is significant!  I normally wouldn't worry so much, but this person really has been rumored to have hiv and that scares me to death!

So let me finish with the main two questions I NEED answers to:

How encouraging is a 4 week test?

How much blood is needed for infection when contacting a 1 1/2 day old would?

The past help from members here has been wonderful, but since I am still so nervous, here I am posting again.  Thanks guys.

[Teak]

Go and reread the answers that you were already given for this non risk issue.

[freaked_out_again]

Just did.  It helped.  like you said before, a person would have to be bleeding profusely for their to be a risk.  I just can't get myself to believe that hough (not saying you are wrong at all).  Thanks again teak.