Why didn't Luke go back to Dagobah in between TESB and ROTJ

I guess he was afraid to face the truth about his father, but it seems like his skills grew quite a bit in between the movies for someone receiving no training.

 

He was trying to find Han.

 

The midi-clorians told him not to.

Of course, they also told him force choking was ok, that hottie Leia is all his and to please stay away from Father Merrick.

 

He was fighting this galactic civil war... the one the rebels were trying so hard to win... the one he is one of the leaders of...

Luke's no simple farmboy anymore. He has a lot of great responsibilities now that he's a commander of an army. He can't just go off to train with his master whenever he wants. he has to make difficult decisions and fight the empire whenever there is trouble.

And I think he also got captured by some pirates in one of the novels I read that took place between episodes 5 and 6.

 

not sure about that, but he was looking for han, and preoccupied with the Empire (Marvel Comics) they actually got a superweapon going during thew time called the Tarkin, which he needed to take down