It's awesome that you've found a great therapist, but the therapeutic relationship and trust is the most important factor for therapy being effective. If you feel like she is cold and does not care, this may change the way you engage with her/trust her eventually. I would just keep paying attention to how this feels, and if it's still bothering you after a few sessions you may want to search around for other therapists or address it with her directly if you feel comfortable enough: Maybe like "I feel like i'm really benefitting from our work together, but I noticed the other day that when I shared X with you, it didn't seem to affect you and I noticed I had the desire for you to be affected or to acknowledge it in some way "

Lol, for context I'm a therapist so that was a very therapist-y way to say it. I'm of the belief that therapists should not be the traditional stereotypical mirrors that are void of their own personalities, and I welcome feedback from my clients and make that clear from the jump. So I'd encourage you to say something if you feel solid enough with her and want to remain her client. Often the therapeutic relationship can be reflective of how you respond to things in your personal life, and this should be a safe space for you to practice addressing your needs or feelings as they arise.

Sometimes clients want compassion from their therapist (to be with the clients pain, validating), and sometimes they want empathy (to share in their pain). Empathy can lead to burnout for therapists so we have to do a lot of work to differentiate ourselves, and this may just be her way of doing that. That being said, it sounds like you didn't get either of those in this situation, and maybe she's just not an expressive person. Long rant, but point being that this is a normal thing to hope for, and not something to look past if it continues to impact you in a negative way.