So as the title says, 6 months ago I made an idiotic mistake and had a brief but unprotected sexual intercourse. 

In the time since then I've done 7 or 8 antibody self tests and I recently also had a full blood screen done at a local sex health clinic. Despite all of the self tests being, to the best of my interpretation, negative I worry that they are bogus or that I've misinterpreted the results. I made the mistake of keeping the tests long after the period for which they are valid (1h) for reassurance but when I look at them I sometimes see lines where I could swear there weren't any before. 

The blood tests at the clinic were supposed to put an end to this but they couldn't find a vein so they sent me to the phlebotomy department and I don't remember if the nurse there labeled my blood while I was there so now my brain has gone and convinced itself that they might have put my label on someone else's blood, which is why they've come back negative.

I honestly don't know what to do anymore. I just want this nightmare to end; I want my life back.