Time for a little science . . . .
I'm sure that by now you have learned about the basic "fight or flight response." When you are faced with a unknown stimulus, your brain gets your body ready to kick ass or run. It does this by producing (and increasing) the levels of stress hormones (like adrenaline and cortisol) in your blood. When the stress hormones hit your bloodstream, your heart rate increases, your blood pressure goes up, the capillaries in your extremities constrict to reduce the blood flow, and muscle tension is increased. This reaction get the body "ready" to react in whatever way it needs to.
As these changes take place, we "feel" it as our heart "racing", breathing heavy, hands (and legs) shaking, mouth dryness, and an increase in sweating. I'm sure you have felt this reaction and these things. You know about them. They are very well understood. Now the part that you don't know.
Your parents don't know this. Some of your teachers don't know this. The teachers that DO know this won't tell you, because in the eyes of the law (and your parents) you are an infant. They think that you are incapable of handling this information. So they don't tell you . . . and the teen pregnancy rate climbed again last year <sigh> I can tell you because I don't have to worry about getting fired from being your teacher. I teach my university students this.
It is NOT simply the "fight or flight" response. It is the "fight, flight, or
breed" response. When you are confronted with an "unknown" such as whether this girl will like you or not (have sex with you or not). Your body responds with stress hormones. YES! The very same stress hormones that get your body ready to kick ass or run also get your body ready for "love." So the stress hormones hit the bloodstream and what happens? . . . . Your heart races in your chest, your face flushes, your hands shake, your mouth gets dry, and your muscles get "tight." Does that mean that you are destined to be an awkward geek the rest of your life with no chance at ever getting a GF? . . NO.
Do you remember doing something "exciting" the first time (riding a bike, driving a car, sky-diving)? Do you remember how you felt when confronting that "unknown" (heart racing, etc.)? How do you feel about it now? You have gotten used to it. It is still fun, but it is no longer frightening. This happened because of a couple of processes. One is systematic desensitization. The other is cognitive restructuring. The science explaining these would take too long in a posting (it's too long already isn't it?), but simply put desensitization is the process of being repeatedly exposed to the stimulus and thus reducing your reaction to it. Restructuring is changing the way your think about the stimulus.
For desensitization to work, you simply expose yourself (NOT that way) to the stimulant (girls) repeatedly. As you do so, your reaction will be lowered to manageable levels. Just go up to girls and talk to them. By doing so, you will reduce your anxiety by getting used to it. Will it be "exciting" the first few times? Yes. However, just like you can ride a bike now without getting "tense", soon you will be able to talk to girls without getting tense.
For restructuring to work you need to "re-frame" what you think about what you feel. You do this by learning and talking to yourself in a positive manner. You are learning some here. Through experience, you will learn more about them. Instead of thinking, "OH SHIT! Here comes a girl!", think, "I am about to have a really good time meeting someone new."
Also understand this, girls mature a bit before boys. She "knows" more about the situation than you do, so she is not as "frightened", but she IS still reacting to the situation. She doesn't think that you are a "geeky little kid" because you get shy and stutter around her. She thinks you are cute. She likes the fact that she excites you. Don't try to hide it. Let her see that you think she is "all that AND a bag of chips!"
And wear a condom!
Peace,
dave