why not זאת אמי שבאה?
I think that sounds ten times better. To me (a native Hebrew and English speaker), זאת אמי באה sounds like a failed attempt to translate from English to Hebrew
Why not also possible: זאת אמאי באה?
אמא שלי = אמי
Welcome to Hebrew.
Some friends study Spanish or Italian and they can make their way after 6 months. After one year of Hebrew I still have to think before counting from one to ten...
Why not אמתי?
אמא שלי = אמי.
אמה (arm, maid, middle finger) = אמתי (pronounced amati).