Months into T therapy I still find that my voice slides into feminine without me even thinking about it. When will my voice permanently break? Has anyone ever been left with an obviously female voice even after years of T?

Unfortunately I have heard of that happening or even no voice changes at all. 

Which would really be devastating so I truly hope that doesn't happen to you.  Just give it more time and I'm sure it will break when it's ready.  A few months is not really that long at all.

It's completely different for everyone. I know a guy who's over 10 months on T and his voice hasn't dropped at all, but I imagine it will do at some point.
After speaking to several men who've been on testosterone for years, they've said that their voices didn't completely finishing dropping and settle until around 2 years.

Thanks, the other changes I've experienced have been better than I expected at this stage but it's the deep voice I want the most