Obviously you’re concerned about this, so my first response is “talk to your doctor”. Have your mother make an appointment for you with your family doctor, if you have one. If you don’t have one, or if money is an issue, talk to the school nurse, who will have seen nearly anything you can present to her, and can make further recommendations if warranted.
But my second response is… I think a big component of this is normal teenage angst. I’ve been there and felt that, and my memory is good enough to recall some of the things that I was self-conscious about at your age. So the second part of my answer is that if you maintain good hygiene (daily showers and cleansing with some kind of soap), then your perspiration will not generally be offensive.
You said (two times) about “feeling the smell”. I think this is part of your (normal) anxiety. That is, you can obviously feel the wetness of perspiration, and you may be likely to think that “it smells”. (The deodorant advertisements are really effective at making you feel this way.)
When I coached teenage boys on soccer teams and we got together in groups at the ends of practices and games, or in huddles on the sidelines during a game—and these boys were dripping sweat—I can’t recall even one time in several years of doing this that I smelled anything offensive.
So try this. Do something strenuous that makes you sweat: take a fast walk in the sun, or run for awhile. Really work up a sweat. Then ask a close girlfriend to spend some time near you and tell you honestly if you smell bad. I’m betting that you don’t, and if she can convince you—even if you’re dripping with sweat—that she can’t smell anything, this may help to put to rest some of your anxiety.
And if you do have an odor that you or others find offensive, many times that can be traced to diet. So pay attention to what you eat, and try to cut out things like garlic, that can affect body odor. It might also help to cut down on makeup, so that more of your skin (your face, primarily) is exposed to air, which can cut down perspiration elsewhere.