I grew up in an extended family household. When I was young, my entire family lived together in one really large house (exactly like the Ewing family did on Dallas). I was the only child and everyone else in the household were aunts and uncles, my mother and my maternal grandparents. Eleven years separated me from my mothers youngest sibling. I heard my aunts and uncles, and my mother, call my grandparents "mom" and "dad" so I did the same. Until the day they passed, I always called my grandparents "mom" and "dad" and rarely ever "grandma" and "grandpa". I still do when I talk about them. Everyone else referred to my mother by her first name so I did the same. I've always called my mother by her first name since I could speak. Occasionally I will call her "mom" or "mother" if I am referring to her to someone. It's been like this for 41 years. Not one time have I ever felt like I was disrespecting my mother nor has she ever thought I was disrespecting her because I call her by her first name. I've never had any friends, co-workers, teachers or family friends think my calling her by her first name odd, either. No one has ever chastised me for it or told me I was being "disrespectful" to her for it.
I have an incredible and unwavering amount of respect for my mother and I don't feel that how I address her diminishes that in any way. I knew people in school who called their parents "mom" and "dad" and didn't have an ounce of respect for them. There is more to respect than the use of a certain title.