You are a brave and smart girl. You diagnosed your problem and you are trying to find a solution for it. Something that many adults are not able to do. You are in an environment that makes it easy for you to get bad habits. But everything happens in your mind. If you want an excuse to use weed, you have it. In your parents, your friends, your school, .... The day you STOP making excuses and realize how using weed ruins your life, everything will be much easier. You are smart enough to understand the root of your problem. "loneliness" . I add to that " lack of self-confidence". But that's very normal at your age and even for adults. Look around a bit deeper. Even the funniest, prettiest, wealthiest kid or adult has insecurities.
You don't need to be liked by EVERYONE. You don't need to use weed to look cool. All these "friends" will go away in a few years and you will be alone with an addiction that will ruin your chances to have an education and a better life and real friends! Do something that you like. Find confidence in pursuing a passion. What are you good at? Or what do you like to be good at? Start with it.
A sport, a subject at school. Try very hard to be the best in that and don't worry if you fail a few times. Just keep trying. when you start having those good feelings of success and confidence back, you will not be lonely anymore. You have your passion and many will look up at you. You are such a wise girl, I am sure you can do whatever you want. Find someone that you can trust and talk to and start something to do. Reduce the numner of times you do weed gradually. Replace it with something else. (run, chew gum,go for a walk, ....) . I hope I come here one day and read a message from you saying you have quit completely. I tell you something else. You can be a psychologist or a councelor. You can help other kids out of a similar hole. Big hugs and best wishes to you.