You become Buddha when you forget everything you learnt in your Bodhisattva training.
(paraphrasing Einstein's: Education is what remains after one has forgotten everything he learned in school)
And Nirvana is indeed the state you reach when you do not search for Nirvana anymore - in neither the direct way nor the alternative ways, like drinking or making money. I mean, when you don't search anything from making money anymore ;) It's just what remains, the beautiful and glorious world, where everything is perfect, perfectly happening. Nirvana is what remains ..and it's beautiful indeed.
BTW I'm not there right now, I just found out another detail to forget - I did learn it in my Bodhisattva training indeed. In that old, old life I hardly even remember. But still more things to forget before it flashes to me like new, all the experiences, all the good stuff from numerous lives, as a perfect crystal, the perfect destiny of something unique, something completely different - everything is completely different and that's why we enjoy. It has not happened before - nothing has happened before as it happens, has never been happened before as it happens and will never be happened before the future, when it happens. So it can make up a perfect crystal - some symmetry in levels we could never imagine before seeing, some symmetry out there, in our lives, in our past, in all the lives and all the lives of all beings ..the universe is all-beautiful, all-colorful, all-practical and it makes a perfect sense. The sense comes from that you can tell that before you see that - you just know, it makes sense. You sometimes see some things making sense and then you know, everything must make sense. What a pleasure to see it :) You just see it for once and if you choose to forget - it's just perfect. Then you choose to forget, but the crystal even grows, growth is possible even in perfect world like ours, it's possible even outside time and space, even outside any borders, even in perfection - the act of growing, the pleasure of growing, it's all there even in the end of time, end of infinity, it still grows, even if all has stopped, it still grows ..that's the only belief I just need to go further - or, I can let it go ;)