I'd definitely recommend practicing your vocal pitches, highs and lows, because the higher (or lower) your voice can go, the lower (or higher) it can go as well.
Tuning it with a guitar. (find your most comfortable voice pitch on a fret, then work your way up or down around it. It doesn't hold for days, but keep doing it and you can stretch it out nicely (just like pumping, hahaha)
Make a lot of noise.
Invest in HRT. It really helps, and my voice was deep before.