Bulimia is the result of thinking a certain way. You are thinking that way, so whether or not you have a certain label or not isn't the problem, the problem is the problem, if you get my drift. It might not be a bad idea to see a therapist to find out if you can stop thinking in such an insecure way. Whether or not your current weight is the right weight for you depends on your height, but most of us can tell by looking into a mirror if our bellies are sticking out too much, or if our clothes don't fit anymore. I mean, if you're 4'11" and not muscular, that might be too much weight, but throwing up won't fix it in a healthy way. Obsessing over it won't do that, either. If you are overweight, and I have no idea if you are or not, you either choose to alter your diet and exercise more or you don't but you don't obsess over it and take it as a sign of your self-worth. If you're doing the latter, that's your bigger problem, and one that you ought to consider addressing.
He, I'm sorry you are feeling this way. So, I've not been exactly in your shoes but have had my own battles with how I see myself and my body. Body dysmorphic disorder is when you don't really see yourself as you are and also have unrealistic expectations for yourself. I never made myself throw up but I definitely would binge and then starve. I went through a period in which I ate virtually nothing and exercised three hours a day. Yikes. Finally, I went to the doctor because I was fatigued and he made it clear I wasn't getting enough calories. Having kids and getting older really gave me a new perspective.
What really helps or at least it did me was shifting mindset from end result to process. Lifestyle choices and not just being skinny. Just like at school. When you have a really hard class in a subject you struggle with, if you say "I have to get an A" and take short cuts, it probably won't happen. But if you make good decisions throughout and prepare, study and do your best, you will likely feel good with the end result even if it is a B and not an A. The process is important and that is within your control. The end result isn't always.
One time putting a finger down your throat doesn't make you bulimic but if you are constantly hyper focusing on your weight and trying to control it through drastic means, then you are headed down a difficult path. So, switch it. Focus on process. Exercise several days a week (nothing crazy like the 3 hours I did), eat healthy. get rest.
Tell us more and we'll try to help!
You know, perhaps your family is part of it but eating disorders also just happen. It's a mental health issue or it can be. I was borderline. Not something I sought treatment for as life eventually just ironed it out. It is NOT normal to make yourself throw up after eating. That's not good for you in any way and takes its toll eventually. Even on things like your teeth. Being encouraged to watch your weight though is not a bad thing in my opinion. We all need to eat healthy and exercise. If you are doing those things and are not a twig that is fine. If you are eating taco bell 5 times a week while watching tv, not so great. We all have a natural body type. We can't do much about that and yours may not be the thin frame your family has but you also have to focus on a healthy lifestyle. That means, not making yourself throw up, not starving yourself, not trying to exercise at times like you are training for the Olympics, making good overall food choices, Moderately exercising often, getting rest, etc.
So with all that said, I'm not really sure where you fall into things. I've had anxiety about weight especially in my youth. I've stressed and used food in the wrong way to either control my life (anorexia is a lot about control when you don't feel like you have control elsewhere) or to comfort myself. I'm thrilled and happy you are seeing a therapist. Please DO talk to them about this subject and get some feedback from the professional working with you. Let us know how it goes!