I need help writing something in Spanish.

My baby sister is interested in learning Spanish so I wanted to write her birthday card in Spanish to give her some practice. Unfortunately my own Spanish is limited, so I need someone to proofread my work and make sure I'm not mangling it!

I want to say:
I call you "La Princessa" because you are very spoiled, but you know that I say it with love. On your birthday you deserve to be spoiled by everyone! I hope that you have a wonderful birthday!

What I came up with is:
Te llamo "La Princessa" porque tu eres muy consentido, pero sabes que lo digo con amor. En tu cumpleanos mereces ser consentido por todos. Espero que tengas un cumpleanos maravilloso!