A minimum of 2,500 calories?

I have been struggling with my weight and eating issues since about September. I am 5'4" and currently weigh around 78 pounds. I am eating 1,000-1,100 calories a day, at the most. I know that's not a lot, but it's double or even a little more than double what I used to eat. I have always been skinny my whole life, but at this height, I used to always weigh around 95-98 pounds. I think I was 100 at my most at this height. Anyway, I am trying to recover, and I am going to see a nutritionist for the first time this upcoming week. A few people who have recovered from anorexia have told me that you need to eat a minimum of 2,000-2,500 calories a day to restore your metabolism. If anyone has done this, can you tell me if that is true and how it went for you? I can't imagine eating that much and not gaining a ton of weight, but girls have told me that they need that, sometimes more, to even maintain weight. Why is that the case when other people who are recovering say they gain like crazy on very little? I am so confused and scared. I don't want to gain a ton of weight. 10 pounds would be more than enough for me. Thank you for listening and hopefully for the advice.