Does anyone elses child call you by your first name?

Does anyone else’s child call them by their first name? My daughter, 21 months, calls me by my first name. The reason she does so is that her cousin (my niece) calls me by my first name, so she caught on. My niece calls my husband and son by their first names. She calls my sisters by their names as well. But my daughter doesn’t call everyone else by their names, just me. Here and there, she says “mommy” but always goes back to calling me by my first name. I tell her, “please don’t call me _; I’m ‘Mommy’” Sometimes she listens and understands what I’m saying, but most times goes right back to saying it. It really aggravates me, especially when I’m not in the mood & I really want to break the habit. I hate being frustrated over something so little, but I can’t help but feel this way. She’s only 21 months old. Her twin brother calls me mama, but I’m worried he’ll start picking up on calling me by my first name as well. Am I overreacting by not wanting my child to call me by my first name? I want to be called “mama, mommy” all the normal stuff!!! She calls my husband “daddy,” calls my mother “Nana,” my father “Papa,” and in-laws “Abuela/Abuelo” she even calls her brother “Buda” WHY ME??