If you are referring to a birthday in the future, you can say, “How old will you be?” Or, “Which birthday is it?” If you are referring to a birthday in the past, you can say, “Which birthday was it?” Or, “How old are you now?”

First of all, you would say I have a birthday tomorrow or I will have a birthday tomorrow. The most natural way to say it would be tomorrow's my birthday. You would say I had a birthday yesterday. You have to be very careful about asking how old the person is because it is considered very impolite unless you are very close in age or a very, very good friend or relative of the individual. If I am asking a very young person, who would probably be proud to be getting older, the natural way of asking the question would be, "Congratulations! How old does that make you?" Or, you could just say how old are you now? When you say super natural, I assume that you mean something very natural and colloquial, and not something supernatural meaning otherworldly.

One supernatural way to ask about someone's birthday could be: "What day did the stars align to bless us with your presence?" This phrase uses figurative language and implies that the person's birthday is a special and magical event. Alternatively, you could say: "Which anniversary of your birth is this?" This phrasing uses a more formal tone and emphasizes the fact that the person's birthday is an annual event that recurs each year.

I like your use of "super natural" which is correct, cute, and also a pun on the word "supernatural". "What birthday was that?" sounds good to me. You can also say "which birthday". You can't "had" a birthday tomorrow. Say "I have a birthday tomorrow" or "will have". Happy Birthday, Jessicamessica. I love your name.