I am so proud of you. I am sure it was difficult to admit to something like this and especially to tell your mom. I see so many kids like you in my line of work who start just like you did and end up in such terrible situations. It is a brave thing to stop and confront this issue. I know it feels really crummy right now, but I hope you feel some pride in yourself for toughing the withdrawal out and not giving in to the temptation to take the drugs again. I wonder if part of the reason you feel better during the day is because of how active you are. At night, when you slow down, your body and mind have fewer distractions from the symptoms of the withdrawal. When you are feeling crummy, try going for a run or doing some sort of physical activity with your family. Maybe that will help.
Stay with it and keep your mom and other positive influences close to you!