Yeah when Charlotte is on the couch, she's supposed to function as kind of a "cock block" while she's there (until MC "defeats" her"). If you want to fool around with Meredith, you have to talk to her in the morning in the kitchen to replay the old scenes.
It sounds like you're really close to the end of the currently available content for both Meredith and Charlotte (where you'll get a To Be Continued popup).
I don't remember the exact sequence of events for Charlotte, but if she's still wearing her red sweater, repeatedly ask her if you can "Take Her Coat." There's an event in the Afternoon in Brooke's room where Charlotte plays her records backwards, looking for hidden messages.
Lastly, if you haven't, make sure you check out the upstairs bathroom at Midday. ;)
Cheers!