After a year on T it's "highly unlikely" that you'll get pregnant, but T is not a reliable birth control and shouldn't be trusted to be one.
You can stop taking T after you start taking it as long as you still have the ovaries, but if you have them removed the body won't produce sufficient sex hormone of either kind to stave off osteoporosis so you'll have to take either T or Estrogen to keep healthy.
However, if you stop taking T after taking it for a while, some of the T changes will go back a bit. Fat redistrobution and such. However, the facial/body hair, downstairs growth, and such, won't go away. So...
