Samantha - I don't think singing bass will help. You really need to work on extending your upper register.
I was exceptionally lucky that my voice never properly broke and, I suppose that as a male I was technically a counter-tenor, although once the hormones kicked in and changed the timbre of the voice that morphed graciously into an easy contralto.
I have a pretty good vocal range but irritatingly am just about half an octave short of being able to tackle soprano. It's a real shame because I perform in amateur opera and all the contralto parts are always the fat old birds! So even when I was in my twenties if I ever got a major part I always ended up being made up to look about 103 years old and playing the part of dowager duchess something or other - who was some mad old granny! - not exactly every girls dream - but I shouldn't grumble I suppose because at least I have a normal female singing voice.
Anyway to return to your problem, most bass voices have a mode called falsetto - which involves closing off part of the throat, my singing teacher used to describe it as feeling like singing down a constricted drain pipe! Using falsetto may help you, because I think some of the MtF's learn how to make a falsetto speaking voice sound natuaral, and thus become able to make a reasonably good facsimilie of a female sound.
I think you should practice finding and using your falsetto range - using it you may find that you can sing a contralto part. Actually most female pop singers seem to sing within the contralto range - for example KT Tunstall and Amy Macdonald to name but two off the top of my head. In addition lots of musicals have parts which are performable by the contralto female voice - I have personally sung the part of Eliza in "My Fair Lady" for example.
So practice your falsetto because merely usinsg and strengthening your bass register is not really going to help much.
I don't know if any of that is helpful - but I hope so
