luke never uses his lightsaber again after his training on the falcon

That explains Leia's growth spurt when she is shown to be just one foot shorter than Han. In ESB.

There technically is: Splinter of the Mind's Eye

When Star Wars was still in production, there were actually two sequels. Splinter was the low budget version - in case Star Wars did not do well. Because Star Wars was a hit, Lucas got his big budget version for the sequel, and while the film version Splinter was abandoned, the book was not. It was still released and became a best seller.

I remember reading it as an early teen. It was retroactively placed as two years after the original film, one year before Empire.

https://en.wikipedia.org/wiki/Splinter_of_the_Mind's_Eye

In 1976, Alan Dean Foster was contracted to ghostwrite a novelization of Star Wars. Foster was given some drafts of the script, rough footage, and production paintings for use as source material in fleshing out the novel. His contract also required a second novel, to be used as a basis for a low-budget sequel to Star Wars in case the film was not successful....

An additional sequel novel was planned, but by the time Splinter of the Mind's Eye was published, Star Wars had broken box office records. The film adaptation of Splinter of the Mind's Eye was abandoned in favor of Lucas's vision of a big-budget sequel (The Empire Strikes Back). Nevertheless, riding on the success of the film in its first year of release, the book became a bestseller. It was reprinted in 1994 as Classic Star Wars: Splinter of the Mind's Eye, and retroactively placed two years after the original film, or one year before The Empire Strikes Back.