I put "amorous" too, and it was marked wrong. I checked it in a dictionary, and apparently the French for "amorous" is "amoureux" (or "amoureuse").
For a written translation, it may be either "je suis amoureux" "(m) or "je suis amoureuse" (f). From a "type what you hear" exercise, you must put the feminine version to write exactly what was said. "Amoureux" may be singular or plural but it is obviously singular in your sentence.