With you being a female, your chances of the result coming back under have increased.
With a reading of 47 that indicates about 4 units of alcohol in your system, whereas for a man this would be nearer 7.
With the 54 minute delay, I would anticipate that your reading in blood will be in the range of 76 to 84, but 6 is deducted by the laboratory before they send the result back to the police, so that produces 70 to 76 as the final reading, with the legal limit being 80. That is assuming that everything you have said is correct. (I am not suggesting that you are telling lies.... just that sometimes people simply forget a drink or two.....)
I do not believe that the sleeping tablets would have any effect on the result.
Sorry for presuming you are a male, you gave no indication of your gender in your post (not that you need to!) but 83% of drink drivers are male according to the statistics.