Fallon, you will not get fat because of that one meal, or the fact that you haven't been able to exercise since yesterday. You seem to be forgetting that your body requires at least 2000kcals a day just to maintain your weight and function properly. It takes a 3500kcal surplus on top of your daily maintenance to gain a single pound of body fat. For an average woman that would mean having to eat a minimum of 5500kcals in a single day. I extremely doubt your meal on top of the details of what you posted several weeks back of your typical day, which, let's be honest, is not enough for a girl your age to maintain a healthy weight, even comes near that number.
You stress that your weight is (just!) within the healthy range. It doesn't matter. Eating disorders are not physical illnesses, they are mental illnesses that revolve around your feelings, views and beliefs about food and yourself. For example, many people with Anorexia Nervosa start off losing weight when they are overweight. But just because you have a healthy weight it doesn't mean at all that you have a healthy mind. Sorry to bring it back to me, but I'm now well within a healthy weight, but recently I've been battling a relapse, and have lost weight. Despite the fact I'm now physically healthy, my obsessions around weight, food and body shape are as disordered, or even perhaps stronger than ever as I come to terms with my new weight.
I saw your posts in the 'What have you eaten today thread'. As I said several weeks ago to you, filling up on Diet Coke to suppress your appetite is clearly disordered, and you are putting your health at risk. I posted to you several weeks ago about how it doesn't matter if you are eating three small meals a day, if it is not the calorie amount required by your body to function properly then you will lose weight, and ultimately risk malnourishment through lack of vitamins, fats, proteins and carbohydrates. Losing excessive weight doesn't make you happy, it just starts a vicious cycle in which you are never satisfied and slowly dig yourself a grave as your body feeds on itself in the absence of sufficient glucose and sufficient fat. You will witness your body begin to shut down, get tired doing any sort of activity, suffer extreme depression and dysmorphia, and run the serious health risks associated with eating disorders including osteoporosis, bradycardia, hypoglycaemia, and infertility amongst many others. If you are already not eating properly, which face it, you're not, then being bloated is inevitable as your body fills up quicker.
Does that make you think that being skinny will make you happy? I lost 7 stone in a year with my disorder, did I feel happy? Nope. All I wanted to become was thinner, fuelling a depressive cycle that just sustained the anorexia and made me repetitively isolate myself from my friends and family and just made me want to take my own life. All alongside seriously damaging my body constantly running along the thin line of being admitted as an inpatient and being sectioned. Thinness doesn't equal happiness!
We are only too willing to help you on here, but you just need to admit to yourself that you clearly suffer from disordered behaviours. My advice will be the same as everyone else's – get help now! At the end of the day I don't mean to be harsh, I just don't want someone to waste away their life and put their body and mind through the hell in the way that I did.