YA ballet fiction, gawky teenager, spoiled sister Rose favourite in family

Fiction series 80s/early 90s, ballet themed, about a ' gawky' teenage girl with a spoiled younger sister called Rose. Girl discovers that she is really good at ballet herself, and as the series develops has to decide whether she wants to follow a ballet career in a school or become a doctor. The cover of the first book features the girl in the foreground sitting down facing us and Rose in the background, with blonde hair and pink face screwed up with a jeering expression, looking at her.

Remembered lines, 'sitting there with egos like giant puffballs' narrators voice
' I'm always postponing decisions' ballet school head / teacher
What do you mean how long does it take? It takes nine months! I thought you were the one that was so hot on biology!' Girl's mother

Loved this series, wish I could remember what the name of the main character is,but anybody know what this series was called?

I think this is Hi there, supermouse by Jean Ure. I had the edition with the cover you describe. There is a sequel called Nicola Mimosa.

It most certainly is! I don't think I ever would have remembered a title like that, thank you so much!

You're welcome! Jean Ure wrote some great books about young people and ballet - A proper little Nooryeff was my favourite.