NNSV is absolutely correct. Sex is marriage, therefore there is no such thing as pre-marital sex as it's impossible to have pre-marital sex, when sex is marriage. That's why you don't find any mention of pre-marital sex in the bible. And no, fornication does not mean sex before marriage. It means immorailty. Both sexual or otherwise. It can be adultery, sleeping with animals, laying with a man as a woman and incest. But it can also mean a turning away from God or idol worship. (and many other forms of immorality)
Fornication is really a "blanket" term to cover many different kinds of immorality as there was no greek or hebrew word for fornication, the original word in use was pornea and is still in debate to this day because it covers so many forms of immorality. Which btw, was most commonly used to refer to prostitutes and is where we derive our word pornography. Pre-marital sex is a man made term to control people. They didn't want their young daughters falling for someone and becoming "joined in the flesh", because they'd be married in the eyes of God. So, we use scare tactics like, pre-marital sex is sin but as you see, twisting the Word of God only leads to destruction, which is evident in our culture today.
There are people who say, "I respect the sanctity of marriage so, I'm just going to sleep around until I find the one, then I'll take it serious." Wrong attitude and this person has collected countless husbands or wives in the process.
We have taught the message improperly and the truth is, many people had several husbands or wives before the got "legally" married and are committing adultery with the one they are legally married to. People want to deny the Truth in the bible to cover their sins but, "what God has joined together, let no man separate". Ever heard someone say, "my daughter is pregnant, so they need to get married to make it right in the eyes of God."? Of course, but this is a falsehood and thinking a civil certificate or earthly ceremony makes any difference to God, is just silly. It's as silly as thinking a civil court divorce, actually divorces you in the eyes of God.
The last thing you usually here is, "Well, you have to follow the laws of the land, according to the bible". You're absolutely right! But, having sex with someone without a civil marriage certificate or not having a ceremony, is not against the law. I have much more on this topic, but I have to run for now.
God Bless and my God continue to lead you into all Truth.