Agreed with Schrodingerdog, I would take a taxi or Cabify/Uber. I would have zero concern doing so as a solo female traveler (I am one) in Spain at any time of day. And as you say you have a lot of luggage, that would be far more convenient. I’m also guessing cost isn’t a concern if traveling in business class and shopping a lot. I would simply take a taxi.
There shouldn’t be any traffic at that time of day.