The original Nusach Sefard came from places like yemen & spain (I believe), and it was not a break-off from Nusach Ashkenaz. There is no nusach that’s better (in both opinions) than the other.
So, whatever your family minhag is, you should proabaly follow that.
As @CommonSaychel so wisely put it: your nusach is no one else’s concern. Other people can’t tell you to change your nusach.
