A last ditch effort to rebuild the Jedi Order, Luke Skywalker attempts the impossible lessons he learns from a secretly sent holocron to recreate Hego Damask’s experiments of Pregnancies through the Force. He failed. In some ways, he tried the In Vitro Fertilization with heterologous cloning. That failed. Several Imperial scientists that turned to the Rebels before being brought up on war crimes said it cannot be done. That the Force won’t allow biological manipulation like that. Luke Skywalker did not believe it. But with the help of a few of his new trainees, he was able to product one successful living fetus to parturition, and then, he had to give this child up at age 4.
Basically, Luke messed up. Recreating the Jedi Order with more Force sensitive users cannot be rushed. There are no short cuts to become a Jedi. Becoming a Jedi is a natural process, some are born into it, some have talent, like a ray of sunshine. The Jedi Order had its time and now, it must become something new. The Force knows when.