I got a blood pregnancy test done today (5 weeks and one day since my last encounter). Can I trust the result if it comes back negative?

Simple Question. Please, this is a simple question and does not need to be asked over and over. You are not pregnant. The test was done well past any date that would be doubtful.
Yes. Had you become pregnant from sex five weeks ago, a blood test for pregnancy would be positive. A negative test will rule out pregnancy, if the test is done correctly.