Doing a bit of googling, it appears that there are roughly 3 times as many instances of male to female transgendering than female to male.
Is there any particular reason for this 'imbalance'?
Back onto the original post and question.
Yes I've seen this imbalanced described before and it strikes me that there might be two explanations (probably many more) based on developmental biology and societal factors.
On biology, there is an acceptance in embryonic development that the 'default' developmental process it toward female with development of male features being a kind of alternative to the default driven by various hormones etc. So perhaps it is more likely for a person who developed physically male to remain psychotically female, rather than the other way around.
On society - I think it remains easiest and more societally acceptable for a woman to dress and act in a manner more normally associated with men rather than the other way around. So perhaps it is easier for people with female to male transgender tendencies to deal with them without considering them overtly transgender, merely by living in a manner that society accepts as being a one end of the spectrum of what is seen as acceptably 'female' (if you get my drift). For men I think society is much less likely to accept someone as 'a man' while dressing, acting etc is a very 'female' manner. Thus they are more likely to feel the need to consider themselves as more overtly transgender if they are to address the disconnect between physical and psychological gender.
Just some thoughts.
In general terms I agree with you.
Some thoughts:
Not only is the male (at least in mammals) a "modified female", but also, in many measures which are normally distributed, males show greater variability than females. In other animals, sex is strictly an activity concerned with reproduction. In humans, sex has a much more complex role and is expressive and affective. Sexuality is a very complex property for whose appropriate expression in mature individuals a number of influences are probably responsible. It may be that some interactions between inheritance and experience have a greater effect in males than females - hence the greater likelihood of some kind of sexual dysmorphia in males.
A more personal view: when I was a child, it was clear that girls were treated with greater flexibility and latitude than boys. Girls were almost always given preferential treatment over boys, were allowed to be more openly emotional than boys, girls were praised more readily, standards of behaviour for boys were more strict than for girls. (At about the age of seven, I recall the headmistress allowing girls into school buildings to shelter from rain, boys having to stay outside.)
Such treatment at a time when psychosexual development was in progress may have resulted in some learned condition in which being female was a preferred option.
Girls: sugar and spice and all things nice.
Boys: slugs and snails and puppy dogs' tails.
I would hope that such distinctions do not apply today - but I don't know ...