Well Doll, between you, me, and the internet, I do happen to think that the paranoia regarding 'socializing' a dog is rather overblown at times. I've known enough dogs when I was growing up who spent the majority of the time in their large yards or houses from puppyhood. Occasionally, they'd get out for walks and behave just fine around other people and dogs. Sure, it usually takes a moment for settling down, esp. with a younger dog. But there wasn't this 'pressure' to raise the perfect dog that would be 'wrecked' if a single step was left out.
Yes, your apprehension can transmit itself down the leash to your dog. He also feels how you react from being right next to your leg. He might be more 'assertive' when the Bostons are with him because of simple pack mentality of safety in numbers :) There's a lot of things that he could be 'thinking'...but it's how you treat his behavior that truly matters, imo. :)
Remember, every spot he's in, he will view differently. Inside your house, your yard, your car, even certain parts of the walk... it depends on his feeling of security, territory, other 'buds', and his mood. Watch him and learn where he's predictable... then anticipate his reaction, and last minute, do a quick change of your behavior that forces him to pay more attn to you than someone else :) I like to keep my crew off balance... It's when I grow complacent and predictable that they tend to act up :P :)
hth makes you feel a bit better... just remember though, I"m no expert and this is just 'stuff' that I've felt out over the years, so it's not gospel truth. Just go with what 'feels right/natural and the two of you will be able to find out the right 'path' for you :) Geesh, I'm sounding like an evangelist now :P :) :D
regards,
toodles