Infinite number of planets with life

[Hovik]

there is no end for the universe, right?

Actually, we know not only how big across the observable universe is, but also how much mass is in it.

our planet is pretty "lucky" in his position with the sun, some centimeters away : to cold, some cm near: to hot...

This is also untrue. The habitable zone is estimated to be some 2.28 AU wide. Furthermore, the Earth's orbit is elliptical, so its distance from the sun varies between 152 million kilometers at its aphelion and 147 million kilometers at its perihelion. That's certainly not a difference of centimeters.

Edited to fix my failure to include observable.