Do the dedicated, die-hard and fanatic medals also depens on the number of people who see what you post?

Yes and no.
In your case, no one sees it and so then no one votes on it.
In order to get a medal in a club you have to have alot of people like your pictures.
Or you have to have a lot of people answer your teste questions.
Or both.
So yeah if there are only 2 people I don't think you can get the medal.