Get tested.....if you don't, this fear will continue to be with you no matter WHAT anyone says. I know how scary it is, but my best guess is that you are are HIV negative and suffering from anxiety.
If you contracted HIV, then yes - you would still have antibodies on testing years later. If you are concerned about a possible exposure to HIV and have not been tested, call your health department and inquire about the testing. They have staff trained to do pre and post test counseling on all HIV and HCV (Hep C, which - if you go for testing - they may also test you for). If you think you've been exposed to either at anytime in your life, get tested. Best of luck.
Look in the HIV Prevention forum. There is a wealth of information there.
It seems clear to me that after 6 weeks you are clear if no antibodies show up on a screening. But don't take my word for it, go do a search at the HIV Prevention forum. You'll find all the answers you need to put your mind at ease.