I would just share with T what's going on with your thoughts on changing session frequency. If you agreed readily to her suggestion, she probably doesn't know about your anxiety and fears about the change.

When I changed from therapy once a week to once every other week, it was hard at first. After a few months, I told T about the difficulties I was having, and he suggested I go every other week for 90 minutes instead of 50. This helped immensely! So once I shared the trouble with T, he was able to help. So don't keep what's going on to yourself. Your T may have some ideas on how to make the transition easier.