Translation of single-minded in German

So by age twelve, I had decided that I wanted to learn English and I was studying for the United States TOEFL at age twenty. Being bilingual practically from birth, makes speaking languages very easy for me.
If you go to the shopping mall to buy shoes, it takes an hour and two stores until you find the right pair of shoes. But if you go shopping 'stuff' generally, it might take you an entire day to finish.
Actually, the East Coast is six hours behind CET, that means that I would speak on midnight at your 6 o'clock dinner. We should try written exercise first because of the huge time difference.