How to tell my therapist I'm aro?

I really want to approach this topic with my psychologist but I'm afraid it will either be dismissed or she'll take it as a sign of something else going on with me and the last thing I want is having her looking for some trauma that isn't there. For context, I'm aroace but the aro aspect is more relevant for me.

I'm very nervous about this, so if you have any advice on how to bring this topic to my therapist I would really appreciate it. If you share your own experience it would be very valuable for me too.