When my T is away, the way I deal with it is by pulling away. It's a good way to cope but it doesn't mean it is permanent.
I can feel perfectly fine during breaks, and even question my being in therapy, and when she returns the first session might be a little rough but now I know that we can reconnect, even if it doesn't happen in that first session she's back becuase that first session seems to be where I pout because she was away, so I push her away in that first session. (which we know is about making my voice heard, retaliating, etc)

The fear is there, even if she reassured you, because they are such different things.
The fear may have to be accepted and even embraced for now. Embraced as it's symbol of sorts for the connection that you do have with T: there is fear because you are connected and you do have a relationship. Sometimes these things just have to be tested to change them, as hard as that it. When she comes back then you will have the added experience of being apart, worrying and being fearful, and then coming back together again
With time, these experiences help the next time feel better.