Yes, your name does literally mean "wine trust" -- but it's the figurative meaning of your name that matters most, particularly if you happen to be of Jewish descent.
Here is what *A Dictionary of Surnames* (Hanks & Hodges) reveals about the many different surnames of German origin which begin with the word "Wein- ":
1. German metonymic occupational name for a producer or seller of wine, from German "wein" ("wine, vine").
2. Jewish (Ashkenazic); largely an ornamental name, reflecting the prominence of wine in the Jewish Scriptures and its use in several Jewish ceremonies. It has been suggested that the surname has been adopted because of the symbolic association of the vine with the Hebrew personal name "Israel" ("they shall thoroughly glean the remnant of Israel as a vine", Jeremiah 6:9).