I absolutely don't think you're being ridiculous! Your concern is sensible and your feelings are valid. I encourage you to ask her the question directly: "Will you still have enough time for me, will we still have my regular time, are you sure you'll be able to keep seeing me long term" etc.

Therapy's all about helping you be better, which means honesty and trust. I hope you can trust her to be honest about your worry and let her address it to help you feel a bit better.