Are my small breasts a result of a hormone deficiency during puberty?

Question
I am a tall, thin female in my mid-20s, but have the breast size of a young adolescent.
I barely have any breast development beyond what I call nubs. My bra size is 34A, but I don't begin to fill it out.
I am extremely self-conscious and certainly that effects my self-esteem and subsequent social life.
However, I am in good mental and physical health except for the size of my breasts, which are not just small but underdeveloped.
I can't say that I know anyone else my age or near my age that has breasts as small as mine.
My mother has small breasts but they are large in comparison to mine. No other immediate or extended female family member has very small breasts.
Someday I may choose breast enlargement but that is costly and I am not sure I want a cosmetic answer.
My question is whether during puberty my body did not produce or release enough of the hormones needed for breasts to grow and that would explain the appearance and size of my breasts which resemble very beginning female puberty or early adolescent breast development?
Can a test be done to determine this and is there any ethical medical treatment to increase breast size?
I compare my breast development to a small person who has a growth hormone deficiency and is short, but I know that the seriousness of mine compared to them is inconsequential.
Could a specific type of doctor be able to help me? I have not asked my GP that question, as I was too embarrassed? I am not fixated on having much larger breasts but actually having breasts would be nice compared to nubs.
I have wondered, given the smallness of my breasts, whether a deficiency during puberty, might have occurred.


Answer
This is not a trivial problem and should receive the same attention as any other medical problem.
Basically, there are two kinds of explanation for your problem – the first is a genetic disorder (even though there is no similar problem in other female family members), and the second is a hormonal problem around puberty.
There is a third group which is patients who have neither of the above problems (a kind of 'all the rest' group).
In the first group, no treatment is likely to help the breast size, but in the second group there may well be effective medical treatments.
See, the issue is not just your appearance, but maybe one day you'd want to have a baby and might want to breastfeed – not possible if your breasts have never developed!
There is also another reason to take this problem seriously – the lack of breast development may be only one sign of an underlying treatable hormonal problem.
There are doctors who specialise in such problems and your GP might even know a local specialist clinic, so I think that (setting embarrassment aside) your first step should be to see your GP.
Ask for a referral to either an endocrinologist (who specialises in hormonal problems), or, maybe a gynaecological endocrinologist (who specialises in hormonal disorders of females).
Good luck. It might be that you discover a successful treatment is just around the corner!
Yours sincerely
The NetDoctor Medical Team