In your dream, you are actually dancing with Jesus. That is why you are portrayed as a gal in your dream. You are the bride of Christ,and the person you are dancing with is Jesus.
Dancing with Jesus means you are actually walking with Him. You are walking with God so much that He refers to your walk with Him as a dance.
Yet, in spite of your close relationship with Jesus, you feel uncertain about yourself. Your uncertainty about your purity before God is reflected in your search for washrooms.
Washroom refers to a place where one is being cleansed, and your search for washroom in your dream shows your desire to be cleansed before God. However, you are already cleansed before God through the blood of Jesus. When you accept Jesus into your life, you are already made perfect in righteousness before God. There is no more need for you to wash yourself before God, and that is why God allows the first washroom you walk to to be used by someone. What God means is that you are pure before Him and there is no need for you to go to any washroom anymore. But you do not believe it, and therefore, you continue to search for washroom where you can make yourself clean before God.
The second washroom you walked to is unlocked and will unlock itself, because God wants to see you in your nakedness. You are not unclean before God but clean, through the blood of Jesus, and therefore you can come to God just as you are, with no need to hide behind a door. God loves you, forgives you and accepts you just as you are. You can be completely transparent and naked before God. There is no need for locked door.
The third washroom is religion, and it is having a religion, instead of a pure walk with Jesus. Your right standing with God is through your walk and faith in Jesus and not in doing religious things. Therefore, the third washroom is powerless.
Finally, you walking back to the used first washroom shows that in your conscience, you feel you need you are not right with God. You feel that there are sins in your life that displease God and you need to continually cleanse yourself before Him. That is why you want to go to a washroom. You want to be cleansed before God.
Yet, the fact remain that you are already cleansed before God. You are forgiven of all your sins and you are completely pure in God's eyes. There is no more need for further cleansing in your life, because CHRIST had cleansed you with His blood. You are now pure and right with God.
Continue to walk with Him, and don't feel condemned when you falter in your walk with Him. You are the pure bride of God. Continue to walk and dance with Jesus.