First — and this is very important — I want you to know that you are not at all alone in this. Many teens are insecure. Even kids who look secure are often as anxious as you are inside.
You have been trying to “cure” your insecurity by limiting the number of people who can reject you to one person at a time. As you have discovered, it doesn’t work to do that. Why? Because the teen years are a time when people sort who they are most comfortable with, who they want as friends, which friendships are healthy and which are not. This leads to a lot of rejections along the way. Kids like you who are sensitive often take this sorting personally, when it is often just about not being the right “fit” for someone else.
The “cure” is to decide to take some risks and to broaden your circle of friends so you can do some sorting of your own. You will only figure out who are the right friends for you by experimenting with different relationships and by comparing how you feel (and even how you are) with a variety of people. It’s just true that sometimes people we think are a perfect match when we first meet them don’t turn out that way. This isn’t heartless. Sorting (which does involve some level of rejection) can be done kindly.
Kids who successfully navigate the peer group are people who find ways to get to know lots of others before settling on a few besties. You can do that by joining teams or clubs or activities that interest you. People who share an interest (whether it is softball, a theatre production, making music or work on a service project) already have something in common. Slow down with trying to get close. Resist the temptation to cling to one person. Instead, do things with the group. Invite a few people to do something like go to a movie or go shopping or something you know will interest them.
As you gain confidence and become a more active participant in the life of your school, you will naturally find your own group. Yes, you will be “rejected” now and then by someone you think might be a friend. But you will also be accepted by others. That’s a normal part of the process.
I often wish there were a way to magically get young people through the struggles of the teen years. But I also know it is those very struggles that are necessary to help you develop maturity and sophistication about relationships. It’s difficult. But I suspect you have what it takes to manage it and become the sensitive, strong woman you are meant to be.
I wish you well.