140 Hz is not the worst if that is your conversational pitch. If your high is at 160, if this is short peaks then this points to me towards some benefit being in allowing yourself more pitch variation (speaking "melody"). Average male range is 100-150 I read, so 140 is on the upper part of that if that is without you trying to increase pitch. From there it is quite possible to go up to 160, which is androgynous to 180 which is female.
The video with the adams apple - i saw that and it is partly correct - to improve resonance (! - not pitch) the larynx has to move up a bit. This takes some practice and there are a half dozen different ways to get into that. I heard Amy describe it as a more deliberate relaxation, others do it by looking at the adams apple, others do that falsetto trick. But to get resonance right is really the more important thing.
If you do not get the sound of the voice to be female even if the pitch is off, increasing pitch will not help much - not even if it is surgically altered.
I am not sure if this works but it should and I am going to try this - I believe in some software like Audacity, there are "filters" to increase pitch. Maybe this can help judging your voice a bit - you could record a clip and filter it to increase pitch to 200 Hz and then see if it sounds female overall. If it does, only the pitch is what is missing. If it still sounds a bit "fake" or like a high pitched male-ish voice, then most VFS would not help to get that away either.
If resonance is right, pitch will for some reason go up a bit anyways - not a whole lot, but a bit.
If there is no way you can get resonance working, the only VFS that can help is the "big one" like Dr Thomas does it - reducing larynx size and elevating its position with sutures.