Hi Chloe,
If passing is important to you, please understand it will probably take at least a couple years. First and foremost, begin facial hair removal immediately -- for most transitioners, it takes at least 18 months of full weekly clearing to get this done, if not longer. Some can get a jump start with laser; almost everyone needs electrolysis to finish the job (if you don't, count yourself lucky).
Concurrently, work on your voice -- women's voices are typically a higher pitch and different timbre. It takes dedicated practice, and a willingness to listen to your recorded voice so you can modify your techniques with more objective feedback. It took me 6 months to find my voice, and another 6 months to make it permanent 24/7.
Strongly consider facial surgery! Seriously. There are significant dimorphic differences in the shape of the forehead brow, nose, chin and mandible between the sexes. They become more discernible as we get older. And don't forget the hair on your head -- preserve it, take care of it, and address any shortcomings as necessary.
To conventionally pass in bed as a heterosexual woman takes bottom surgery.
And that's just the physical aspects of passing. Over time, there will be issues of social expectations, modes of interaction and conversation, for example. There's even more, but that's an entirely different conversation, which is necessarily predicated on getting as a far as I've already described.
All this (except voice practice) will take money. A lot of it. Above all else, stay employed, and the best way to do that is make yourself indispensable to your employer, both in terms of your productivity and how well you promote a harmonious social environment. Also, build up your credit. The more you can borrow, the faster you can go. In the interim, live on the cheap and save like crazy. Finally, take care of your body -- you'll get much better results if you're fit, eating healthy and exercising regularly; being overweight and out of shape leads to many more complications.
This is the material reality that most of us have to face.
