Fear of rejection is natural, but not acting because of it is even worse, because not only you lose her for sure, but it shows you don't think you are worth even trying,... If you do that, you will hate yourself.

As for your situation, it seems she is already quite open to you, so if you want to reduce risk then just try to spend more and more time with her. Even though you don't express your feelings, the fact that she is willing to share more of her time with you is meaningful. In the end, you will have a level of intimacy that you can verbalize it without fear of rejection.