3.The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.
Doesn't this sort of say that you are out after two years if no agreement occurs?
Yep, the treaty obligations end after two year regardless of negotiations. Its a solid way out. Nowhere near as murky as our own constitution.
That does not translate to you having a say. Remember that even during that two-year period, all your voting rights (as little as they are) are cut off and anything can be decided about you without a shred of input.