I think you picked a hard thing to do given the market competition but that doesn't mean you should toss in the towel. You have some non-zero traffic level and there is value to that if you want to continue to see what it can do.

The problem is the site is competing against the large incumbents in the space like Google etc. So you have to differentiate IMO. For example, I assume you are local to many of these restaurants, what about doing interviews, back stories, historical building facts etc. Make it nice for locals and tourists alike to learn a little about the people behind the restaurant as well as the area and history.

My son traveled recently to Ireland and that was one of the things that he and his girlfriend loved, most bars and restaurants had stories or were in some historical building etc. As an American we think old is a building still standing from the late 1800's early 1900's, Europe in general has furniture still in use that is older than some of our buildings. Google isn't going to tell you that, only a hyperlocal search can help people with those cool facts.

That type/level of content I think would help drive additional traffic not to mention differentiate your site from the big players. But you have to be honest with yourself, that takes significant work to cultivate that level of content, and you have to make sure you have a monetization strategy, but I think there is market for that type of stuff.

Just some ideas, YMMV.