maybe just use the old standby wording - its my 6th birthday feel free to treat me like a princess
or just It's my day to be a princess - I'm turning 6
I do like the design and color how about some flowers instead of the confetti or balloons -pink roses maybe?
I have ideas, but no idea how to make these so you are on your own there!! wish I could be of more help!! maybe just put a little tiara and wand up there instead of the other stuff?