It's not only your body that changes when you reach puberty. You start to feel different as well.
Laughing or crying
During puberty you may feel really happy, and then the next minute rather gloomy or sad. You think more about yourself and about the world.
Because so much is changing in your body, you may feel insecure. Do I look good? Do other people like me? You have to get used to your new body. Don't worry: it's all part of it.
Do I look different?
Boys are not all the same. One gets his first ejaculation at 11 years old, another at 16. Perhaps you are taller than your friends are, or have a smaller penis. Don't worry about it.
During puberty, young people often fantasise about someone they fancy. That could be a girl, but it could also be a boy. You may fall in love. Then you get butterflies in your stomach and very nervous when you see that person.
Thinking about sex
You start to get curious about sex during puberty. You think about sex a lot and perhaps you get a feeling of excitement in your body. This site has a lot more information about sex. There are also other websites, or booklets and leaflets.