I'm not feeling like meeting up with my friend.
Why don't you want to meet up with your friend?
I'm afraid that my thoughts might be misunderstood or she might not be satisfied with it.
It is okay to feel anxious about meeting a friend but you shouldn't let that stop you from going to meet a friend. It is not good to stand up a friend, it will hurt their feelings.
I don't think you understand the position I'm in.
Have you considered that maybe your friend will be able to help you if you talk to her? If you're worried about being misunderstood, then you should convey that to your friend so that she can help you work through those feelings. If you can't talk about your problems with your friend, it'll be hard for you to work through them.