Hi Carolyn, welcome to the forum. You have done an excellent job here of lining up the details but unfortunately I will not be of much help.
Julian Tolouse, in Bottle Makers and Their Marks, says the keystone mark alone cannot be pinned to a particular glass manufacturer.
It is possible that the "55" is the year of (glass) manufacture. Legislation which required the "Federal Law Forbids" marking also required markings on the base but these markings are not consistent.
One usually sees a D-### or R-### (distiller or rectifier) which identifies a company - it is possible that this could be D-1. I have been assembling notes on these numbers - for D-1, I have National Distillers Products Corp., Cincinnati, Ohio. I would not count on this...have not cross checked this particular entry against multiple bottles as of yet.
Probably your best bet would be to continue to browse ebay in hopes of finding a similar example, perhaps with a label, or just others marked with D-1. I might recommend searching on "Federal Law Forbids" which will give you lots of bottle results to review.