AIO thinking my (24F) therapist (40F) invalidated my eating disorder?

I (24F) feel like my therapist (40F) invalidated my eating disorder.

Yesterday, during my session, I brought up my disordered eating habits. For context, my eating disorder habits have been going on since my early teens. I never brought it up because I was embarrassed. However, in the past 6 months, I have gained 15 pounds when I used to be underweight. I told my therapist about my habits and what they look like. For example, I explained that when I eat dessert, there is always a voice in my head telling me to stop eating. I gave another example when at work, I ate a donut after I already had breakfast, and spent the rest of the day beating myself up. I also told her that when I feel "bloated", I do not want to eat because I think I am too big to be eating.

My therapist went on to tell me that there is some truth to my thinking regarding the donut. She explained that weight gain is all math and that if I were to eat a donut every day, I would gain weight. She didn't see any logic in my thinking, where I think my whole donut fiasco is problematic because I shouldn't beat myself up for eating something I want.

As the conversation continued, she asked me to go through what I eat in a day. I explained to her that I have a sandwich in the morning, yogurt for lunch, and snacks throughout the day, along with dinner. She went on for about 10 minutes about how maybe I am stress eating and don't realize it, hence causing my weight gain. I emphasized that I am not overweight; I am finally at a healthy weight, but struggling to deal with this new body.

Finally, I told my therapist I don't know how to cope with these disordered eating thoughts in the moment and asked her what to do. She told me to throw away my scale and eat healthy, then I won't feel guilty for having dessert next time.

Am I overreacting? I am heavily considering a new therapist and have been for some time (see my post history...)