It seems like you're succeeding in organizing a perfect wedding!
As for the bartender, it is pretty hard to find a professional out of the agency network.
If the bartender is the only missing part of your wedding, I assume you already found both the location and the wedding planner/restaurant? Why don't you try to get in touch with them to find someone to bar tend at your party?
Otherwise, you can take a look here (http://www.thebartending.com/) or here (http://www.stefanosereni.it/). They're professional bartender agencies. Even if both websites do not have an English version, you can send them an e-mail directly and see if they’ll offer an estimate for their services - they both say it is a service they offer and say to contact them for more information.
Hope this helps!