Unfortunately, you kinda missed the prime socialization period, so you may have to take things slower now. One of the very most important things to do is set her up for success.
For example (off the top of my head), if you know a place is going to scare her, then don't take her directly to that place and just let her "deal with it". Instead try to take it slower, take baby steps. Maybe take her to that place but leave her in the car, sit with her so she is comfortable, and just let her watch out the window and feed her treats. Repeat that until it is routine and she is comfortable. Once you have gotten her comfortable in that situation, then up the criteria a bit by, for example, doing the same thing but not sitting with her. When she is comfortable with that, up it again. Maybe do the same thing but roll the window down this time... Point is, take baby steps and listen to what she is telling you. If she isn't comfortable or isn't "feeling it" one day, fine, don't push it. Try again the next day.
You say she only follows certain people - fine - then take those people with you to new places and let her experience the new places from within her comfort zone. Set her up for success. Socialization is about building POSITIVE associations with the environment - don't flood her! No Cesar Milan techniques - NO FLOODING!
That's my $00.02. I hope it helps.
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