Some well-meaning people really don't have a clue when it comes to determining gender. When they see any blue at all on the cere, they immediately say "male".
Many members of this forum are experienced in determining gender and you have been given the correct determination. Bella is indeed a beautiful girl.
If you'd like to look through the links below, you will then have all the information necessary to explain to your friends on Instagram about gender determination in budgies.
Thank you all so very much it's greatly appreciated it's not nice having some people try telling you different, and I was referred to talk budgies by one who said my Bella is male.
So thank you all again