The sentence is correct grammatically, and as other people have said the word 'do' is used for emphasis but the word 'miracle' isn't used like that. Generally, a 'miracle' is defined as being an act of God, although people generally use the term to describe something amazing that has happened. So it's not something that you have, but something that you have experienced or if you're talking about something that's happened. So you might say -
'It was a miracle!!'
'I saw a miracle today'
'I had a miraculous experience'
I guess you could say it as -
'I do believe I have a miracle waiting to happen to me'
Hope this helps :)