NTA. You picked a ring based on jewelry and designs that you know your girlfriend likes, because you thought it was something that she would want to wear. That's all that matters.

Not everyone cares about price or where the stone is from. This newer adult generation, especially, seems to gravitate a little more toward style and sustainability when it comes to jewelry rather than price and "it has to be a big huge diamond." Obviously some people still care a whole lot about that, but many don't.

The ring my partner proposed to me with was about $150 (and that includes the lifetime warranty) and has all lab-created blue and white sapphires on a silver band. I'm very happy with it. No one can tell it was inexpensive or that the stones weren't mined (most people think the big clear stones on either side of the main blue sapphire are big diamonds, lol) and we love it, so that's all that matters.

You probably know your girlfriend well enough to have picked up if the ring you chose is acceptable to her. All that matters now is if she accepts the proposal, lol.