Alessandra is a gorgeous, classic name that will age beautifully.
Alyssandra is gimmicky and (I'm sorry) -- embarassing. Misspelling a name to force a nn from it is the tail wagging the dog.
Use nn
Alyssa by all means.
Alessandra, nn
Alyssa, still works.
Alessandra, nn Boogety-Boo, works for me as well. As strict as I am with formal names is as lax as I am with nns. Nns are the place for creativity and affection. Let your imagination run free. But formal names are the place for putting one's best foot forward to the world.
Alessandra will always reflect well on your dd and you.
Alessandra, nn
Alessa, would be my very favorite for you.