When you enter puberty, it's not only your body that changes. You start to feel different as well.
Laughing or crying
During puberty, you sometimes feel really happy, and the next minute rather sad. You think more about yourself and about the world.
So much is changing in your body, sometimes you 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.
Everyone is different
Every girl is different. For example, one girl gets her periods before another. Perhaps you are taller than your friends are, or have smaller breasts. Don't worry about it.
During puberty, young people often fantasise about someone they fancy. That could be a boy, but it could also be a girl. You might fall in love. Then you get butterflies in your stomach, and you get 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 maybe you feel horny. Lots of girls like to read about it, to look at pictures or to talk about it with their friends.