First of all, I want to introduce myself. really truly... ist ein bisschen too much meiner Meinung nach. Einfach nur I am really sorry.
I want to say how sorry I am... oder besser: I would like to express my sincerest apologies. I know it sounds odd
I only want lovely things... hm vielleicht: All I want is just to have nice things just like everybody else.
I don't know but understand something is wrong --> komischer Satz, was wolltest du damit sagen?
Overal, I really regret to have stolen from you and I promise that I will never do it again.
Yours very sincerely --> Yours very sincerely and respectfully, falls du noch ein wenig schleimen möchtest, was in einem solchen Fall wohl nicht verkehrt ist ;)
Cheers!