Thanksgiving/Undereater

So today was the day to enjoy eating and pigging out. I knew I was going to pig out. I overfilled my plate because I actually undereat and today I wanted to eat as much as I want and whatever I want. I ate all my food (got one of everything) and still felt hungry, so I went and got dessert. (Overdid it too and got like 6 pieces of different desserts) I couldn't finish all of them and felt so sick. I walked around a big and I puked a bit. It wasn't a lot but I stuffed myself more than usual and feel miserable. Turns out my whole family is worried about me because I am underweight and need help. Plan on seeing a doctor. I never ate so much ever but wanted to because it's a holiday but eating all that has turned against me. Is this what happens if you r an undereater? When you eat more, you get sick? I feel miserable and hate the way I look now. I'm not happy and yes I need to gain weight but I'm always so scared. Am I completely anorexic when I eat more I puke? I'm trying to change my diet but feel scared about changing my diet and I'm just unhappy. What should I do? I know one day isn't going to make me put on weight but I feel like I consumed 5000-10000 calories today. I don't think I will be able to eat tomorrow because of how I feel but I know I will be full on energy and would like to burn it off. How long does it take to recover from a day full of eating to feel better? Sorry for so many questions but I'm stressing over under eating and feeling miserable. Thank you. Please no mean comments, I already feel bad about how I look and feel and I already had another breakdown because of me being so underweight.