[Apologies for the delay. Been busy in RL and I'm also getting ready to go away for a break]
I took a look, late last night, and from playing it right off the bat you have issues and it's probably the relationship levels that's causing them, as that's more than likely the cause of your "problem". That's because when these people achieve their scores they're "removed" from the game, apart from appearing at night, leaving the place looking like a ghost town.
Linda's story Solved
Linda can only have 4 max, and you've not even got to that point yet, as you've not gone away to the beach as it doesn't even show up on the map.
To resolve this. Go see Linda in the afternoon, at her office, to move her story-line along.
Take note of what she says when she's talking to you with regards to going away together.
The scenes gallery confirms this as you don't have those scenes
Caroline's story Solved
You have her on 5 and yet you've not completed her story.
If you had done this then you'd get the message onscreen telling you that you've completed her path, as well as having an onscreen path branch choice when you get to the max score.
I haven't gone all the way through with the Caroline story but it's probably the same with that.
Charles' location is not on screen, so you've still got a way to go to progress her story.
Sara's story. (possibly borked)
Sara is "grounded" and you need to speak to her at school and yet you have her on 5, the max.
This is not achievable with her at the present time. She's nowhere to be seen, and this would be the case if you completed her story to date. From the looks of it you didn't do the conversation in the classroom, because if you did then you'd be able to accept her invitation to chat via webcam in the evening.
However the gallery shows you as having completed her story.
You ignored the webcam show with her, probably due to skipping the conversation about it in school?
Your save show's you as not connected and online, because if you did it would show up on your PC next to Claire's webcam and it doesn't. Also completing her storyline correctly will allow you access to her bedroom during the day and as she's grounded, in your save, you can't go into her bedroom during the daytime.
Your saved game scores
My saved game (completed) scores
The game can only give you a score of 3/5 and you have Sara on the max (5)
Liza and Yasmin
Going by what I can find, see, and do. It looks like you've done their story.
They show in the Gallery and everything looks completed.
Claire's story
Going by txt messages, you've completed (to date) her story.
The neighbours don't show on the phone (as of yet) also the score from them isn't yet available. They were only introduced in V0.6b (Beta version)
From looking around and trying various things that should happen
if you followed the story-line correctly then people would appear at certain times and at the relative meeting points as well.
I suggest that restart the game, from a saved game that doesn't involve spoofing the scores for the characters, because in all probability it's the reason your game isn't working correctly.
I ran your version side by side with my game, and mine worked ok, but yours didn't.
It's not a hard game to do. when playing read what people say in the game. They give you hints in their responses. Follow them and you can progress the storyline.