If I Get my Hormone Levels Regulated, Would This Have an Effect on Breast Size at Age 20?

There is no doubt that altering the balance between the androgen family of hormones such as testosterone and androstenedione and the estrogen family of hormones will alter the size of your breasts.  While it may increase your breast size somewhat, I would not expect that it will increase your breast size as much as an augmentation would.  Good luck.

Breast volume is affected by changes in sex steroid levels. As adjustments are made to levels of the hormones in your body the breasts volume may indeed change. How much is unpredictable.

It is certainly possible that a change in your hormone levels, at your age, could effect breast growth.  It is not possible to determine to what extent.  

Time will tell.  I would give the hormone treatment 6-12 months and then decide.  Your endocrinologist may be able to shed more light on the potential for breast development with this type of treatment.

This question is far better asked of your endocrine specialist, who is aware of your history and your other studies. 

Although some change in breast size is possible, it seems unlikely that this will alter the asymmetry. Nevertheless, if you are considering surgery, it will be best  to wait to see what happens with your change in medication. Best wishes.