Looking for a movie that is not on any typical time travel list. It has a teenage girl (long hair in bell bottoms) who travels back in time and meets a teenage girl who ends up being her mother. They are sitting in a diner and the mom is eating a sandwich. That's all I've got.
It's early 80s, but could it be My Mother Was Never a Kid, based on Francine Pascal's Hangin' Out With CiCi? It involves a teenage girl going back in time and meeting her teenaged mother-to-be.
I would not describe her jeans as "bell-bottom" but she does have long hair, and there is a scene in a diner with a sandwich around 17 minutes in.