PJ:

Without realizing it you are flirting with a heresy known as the "pre-existence of the soul." This heresy believes that everyone who has been conceived first resided in heaven. Their souls ran around heaven waiting, as potential humans, to be assigned parents and be conceived.

The Church teaches that the soul does not pre-exist, but is created individually and uniquely by God at the moment of conception. This means that without conception, no human being exists, potential or otherwise. The only way to justify theologically the notion of a "potential soul" that has not been conceived by whatever means is to assert the heresy of the preexistence of the soul. Don't go there.

There is no such thing as "eternal non-existence". All things in this universe exist. Human souls begin their existence at conception and that human soul will exist forevermore either in heaven or hell after its time on earth. There is no existence before conception and therefore no "potential human" to experience non-existence. There can be no existential experience without an ontological reality. On cannot "become" anything without first "existing".

I advise you to be careful with these many speculations as they can get you in very deep trouble. I have seen people speculate themselves into heresy or even right out of the faith.

Stick to what the Church teaches, and not to dangerous speculations (which, by the way, you are not qualified to do anyway). Read the Catechism and other official Church documents.

God Bless,
Bro. Ignatius Mary