I've bin on estrogen for about a month now and my voice has started kinda cracking and going high pitched randomly, I haven't worked on my voice any yet so I don't think it's anything I'm doing. My voice never really broke when I went through puberty and I never developed an adams apple, so I'm kinda wondering if the HRT is doing something there. To be honest I'm a little worried that my body is producing more testosterone in response and my voice is changing, and although it's more high pitched now is ultimate gonna get deeper. 

Has anyone else experienced anything like this?

I can't say I have experienced anything like that.

Although I have found that since I've been using my new voice for over a year now, it's much harder to drop it down low anymore.