Mom calculated with my birthday and said, I can't be with my current boyfriend. If I get married, it won't be long. He is an only child. ...

Your mother belongs to a feudal ideology, but it is normal. After all, how hard you raise you is to make you live a good life. It's definitely a hidden danger you don't want. You can tell your mother about some constellations or zodiac signs. If you can't, you can only correct it by enlightening your mother's superstitious thoughts.