Translation of schlaff

I hope you could understand my last letter to you. You see, when I write in Spanish I am not very confident. I always question myself and each and every sentence takes about fifteen minutes.
Let me continue to tell you about my adventures. So, as I have told you in my last writing I returned to the airport and scheduled a new date for my flight. This time I left myself five more days.
As soon as I went to bed, incredibly loud music starting playing from right beneath my room. The music was so loud that I could not fall asleep despite my jet lag and despite being extremely tired.