I'm struggling with a similar issue. Thor seems very interested in other dogs, but he is... well, socially challenged. He just recently started letting other dogs sniff him. Before that, he would constantly try to sneak up behind them to get a whiff, but he would run away if they turned around.
He is only three pounds, and he's scared of any dog that's bigger than him. I've been introducing him to tons of other dogs, but he doesn't really seem to know how to play. Yesterday in the park, another yorkie ran up and pinned him.
He gets no respect.
He also gets very upset if I pay attention to another dog, and will emit these horrible, screamy barks to try to chase it away. He even snapped at a Golden last week!
I've been trying controlled meets on the street and lots of praise and treats whenever he behaves normally around another dog. I'm hoping that in a month or two he'll make some progress. It's tough, because I keep taking him to the park to help socialize him, but I wonder if he's just getting more scared.
I'm also thinking small-breed doggy daycare could help. Sigh... patience.
I'm interested to hear other people's suggestions.