High school is a difficult time for many people because students seem to sort into cliques, and if you don't fit into one of those cliques, it is easy to feel as though you don't belong anywhere.  It's a few years until you get to college, where there will be many more people to choose from, and there will be people with whom you feel an affinity, people you can talk to.

In the meantime, perhaps there are places to find new choices for closer friends, places you haven't thought about.  For example, if you have a particular hobby, you might find an organization where you can meet some new people. Sometimes religious institutions have youth groups, and that is a good way to meet people.  An older relative, like an aunt, might be someone that would give you some closeness and some sense of being understood. Finding people to talk to on-line is a possibility, but there are many risks associated with that, so I don't recommend it for someone your age.

If this feeling persists, the feeling of lonely isolation, it would be a good idea for you to get some counseling, through school, through therapy, or through your religious community.  This feeling is something that you should not feel bad or shy about because no one should feel isolated.  We all need to be understood and appreciated.