The promise of all Jews returning to the Holy Land

I come from a pretty non-observant family. So far removed from religious Judaism that no one has a ketubah, or membership to any shul, and some have even moved on to other religions (for serious lack of understanding Judaism to be honest). I have no way to prove in that sense that my mother, and her mother, and her mother etc etc were Jewish so therefore I am too. My Judaism in particular is more cultural, though shomer shabbes…how would someone like me return? The only proof I have is that I was raised Jew-ish, and my great grandparents were buried in Jewish cemeteries. I trust Hashem to do what he says, while at the same time I worry.