First of all, don't expect to leave all your classmates behind. After all, there are very few things that mathematics really likes.
Secondly, be patient with the people you really like. Generally speaking, after the initial training, people who make soy sauce will basically say goodbye by themselves. Although they will take part in any competition, they generally don't care about the development of the community. I wonder if there are any special teachers in your school. It is suggested that you can take time out for training during the summer vacation, so that you can leave real comrades.
Third, internal activities can be serious and lively, with software explanation and friendship;
Fourth, it depends on what you say. For schools, some interesting modeling competitions can be held for some objects in the school, such as the queuing problem in the canteen, which is mainly based on inter-school communication.
Fifth, don't give up if you choose. Loneliness can be seen everywhere on the road to success.
Wish you success! ~