A Company of Swans by Eva Ibbotson 

For nineteen-year-old Harriet Morton, the daughter of an unfeeling widowed professor, life in 1912 Cambridge is no more than a dreary existence completely bereft of happiness and love, except for the moments when she is dancing in Madame Lavarre’s advanced ballet class. When she is offered a position in a touring ballet company that will be performing in the Amazon, her father refuses his permission. Harriet runs away with the company. She makes friends with the star ballerina and falls in love with the wealthy young theater founder, Rom Verney, who is the estranged uncle of a young boy she became friends with back in England. But when her boring would-be fiancée shows up to take her back to England, all of her happiness is put on the line. (Read complete review)