If you were playing vocal music labeled high pitch it may have been a reference to a soprano vocal range. As to why your instrument sounded different may have been the use of sharps more often than flats. Trumpet players are so accustom to be playing in flats that sharps are less comfortable for us. Also, the added sharps tend to place more usage of our more out of tune notes such as C#. Early trombones many times in that period were available with regular tuning slides as well as an optional high pitch tuning slide. The reason for this was to give the player the ability to use slide vibrato in first position.