Any suggestions on how to build up your vocal range and be able to use it in your daily speech?
Practice. Anyone can extend their vocal range. MTF transformation not required. Though in this case I think you want to
move it rather than extend it.
Google is more likely to find you people with personal eperience of your particular situation, but if I were to wildly speculate...I would think the way to do it would be to simply establish a habit of always speaking towards the end of "high as you
comfortably can" pretty much always. Think of the vocal cord as the string of a musical instrument. The tighter you make the string, the higher the note it will produce. But, the longer the string is, the lower it's baseline pitch wil be. Now, think of a muscle. If you stretch it regularly, it will become more flexible over time. And if you work it out without stretching it, it will tend to get tighter and lose range of motion.
So, while length of string is something that might be difficult to affect, tightness of string is easily within your control. Simply keep your string tight all the time, and eventually its "relaxed" state will be a higher pitch than it is now.
Also, I'd suggest a moderate build up over time rather than trying to force years worth of change into a week. Don't hurt yourself.
Caveat emptor. I've never done this nor known anyone who has.
fake edit:
Also, checking around, apparently there are some
cheat techniques you can use to sound more feminine with or without pitch by mimicking secondary speech characteristics.
But yeah, google.