You are the same age as my elder son. Your story makes me feel like crying for you and your parents. They do still love you. They probably got mad because they are at their wits end in knowing how to help you. At least they have locked you in the house - if they did not care they would not have done this.
You have shown you can do 7 months. You need to remember this through what will be a very hard detox again.
There is no such thing as a casual dose of heroin. I think you misspelled that and it should read causal.
Keep close to SR for advice and support.