The Dragonborn book one: gifted

This book is a mix of the HTTYD movies and the wings of fire books. Please do not judge too harshly seeing as this is my first book. I love constructive criticism however and would love it if you guys could give me some ideas for the next chapters and books.so anyway here goes nothing...
Harriet is a young female Viking with no known history on berk. Adopted by the chief of berk and his wife, valka and son hiccup when she washed up on the shores of the isle of berk after a huge storm when she was only a month old she grew up thinking that killing dragons was all there was to the world. Little did she know a prophecy was being fulfilled from the moment she arrived on berk as an infant.