Too and enough are, somewhat, opposite. While too indicates an excess of something, enough implies an adecuate amount; therefore, they are not, strictly speaking, opposites, but convey different enough meanings to be observed in a contrasting manner.

One example use of too in a way that communicates an excess, is if I were to say:

This portfolio thing has taken too much out of my very limited reserve of time.

And an example of enough being used to convey an adecuate amount, is the following:

I think I've written enough of this stuff already. I got other stuff to do.