That's something I'm concerned about, myself. I've only been working on my voice for about 5 weeks now, and I think it sounds ok sometimes, but I still have to think about it when I talk, and I keep unintentionally slipping back down to a lower pitch when I speak.
My voice currently breaks at around G4-A4 depending on whether I've spent an hour warming up first. I want a strong, slightly masculine voice that matches my appearance (I'm tall, thin, and slightly butch?) so I'm ok with sounding a little androgynous; I'm aiming at an average pitch just below middle C but my voice keeps slipping down to the D3-F#3 range when I talk to people. I'm also way too soft-spoken for my tastes. I've always wanted to sound less timid when I speak and I figure as long as I'm working on developing a more feminine voice I may as well add some volume and confidence to it, too.
I don't have any issues with inflection; I had already unknowingly learned to speak using pitch for emphasis instead of volume. I tend to use a more feminine vocabulary and the rounder word sounds, too. I just have issues with voice quality, pitch, and consistency.
Any advice would be appreciated.