First, Nibbana is not a place where you go and enjoy. Actually the meaning of Nibbana is "no craving". When a person is completely rid of greed, hatred and delusion, there is nothing for him to "enjoy". As I have reiterated, you have to change your mindset and adopt a new paradigm in your perception of the universe and existence based on the Buddha's revelation. If we insist on maintaining our stereotyped and limited layman's knowledge of the world and our existence, we will never understand the concept of Nibbana. By the way, the Buddha warned that ordinary mortals like us would never fully understood Nibbana.
As I said Nibbana is unconditioned, meaning, it is nothing like this present state which is subject to impermanence, unsatisfatoriness and insubstantiality. A fully enlightened person will be in a state of Nibbanic bliss here and now, not having to wait for the end of life.
Your comment " I think your nirvana is some sort of eternal existence being merged with your buddha nature, by the way, is buddha nature present in theravada?"
My comment: It is not "my Nirvana", but my understanding of the Buddha's explanation of it. What is Buddha nature? If it means the potential of becoming a Buddha, then it is there in everyone of us. It's just like a seed waiting to sprout given the right conducive conditions.