Dear Mari, 

The main thing that will help you in being open with your spiritual director is to remember why you have one. The reason we have a spiritual director is because we so easily get confused when we try to "self-medicate" spiritually. We are not good judges when it comes to ourselves. So our spiritual director is another set of eyes that helps us see more clearly what we are like and what God wants us to do. 

So, remember that your spiritual director is someone God has placed there to help you recognize his voice and find your way towards him. 

Remember also that her only interest is to help you be a good friend of Jesus, and grow in your relationship with him. Your spiritual director will be able to help you see if your thoughts about the vocation are from God or not, and what you need to do in either case. She will also help you to be strong when you feel week, and find light when you are unsure. 

God bless.