First of all, I want to say that stopping yourself for a full nine months is an impressive accomplishment. Even though you ended up relapsing, you should be proud of yourself for withstanding that long. Bulimia is a serious and very dangerous disorder, and one that is extremely hard to quit on your own. The best way to permanently rid yourself of bulimia is to tell someone about it, whether it be a friend, boyfriend, parent, teacher, or counselor. If you have a person who can be there for you and motivate you to be healthy, it is so much easier to quit than if you try to quit on your own. Bulimia often results in depression and low self-esteem, which is even more reason to find someone who can help you. Don't be afraid to tell someone that you can trust that you have a problem or to ask for their support. Knowing that someone is there for you can really help if you are afraid that you'll relapse, because you won't have to face all of your problems alone.
Just because you already quit once doesn't mean that you can't get more help again from, either from whomever it was that helped you last time or someone new. Asking for help when dealing with a sickness is always a good idea, and the only way that you could be a burden is if you weren't trying to get past bulimia. Since it's obvious that you are trying your hardest to quit, having a friend there to help you may be the deciding factor in whether or not you relapse.
If you don't want to tell someone close to you about your problem, you could always talk to a school counselor or a local doctor about it instead. Bulimia has negative effects both physically and psychologically, and professionals are trained to help you get through everything that comes with the disorder. Help is always available, and anonymity is usually an option.
Above all, try to be kind to yourself. You are a lovable, desirable person. All of us are worthwhile human beings and we all have strengths to go along with our weaknesses. When you can find those strengths and think about yourself positively, it will be easier to deal with the things that would otherwise get you down. Self-esteem plays a large role in eating disorders, and if you are able to raise it to where you can see yourself as a beautiful, talented person, you may not be so tempted to restart. Here is a link that might help you:
Building Self-Esteem.
The best of luck to you with everything, and don't be afraid to message me or any Support Leader if you have questions or just need to talk to someone.
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Sexual innuendo.