Breast development is different for everyone, depending on genetics, so it's hard to predict. But a good indication is to look at the women in your family, taking into regard their pubescent development, and breast size.

Generally the earlier you begin transition(before 25yrs MAX), the larger your breasts will develop. Breast growth for trans women can(though rarely) take up to 10 years to fully complete, again depending on when you began HRT.

As your body becomes an estrogen-filled sack of squishiness, and estrogen begins to make up the larger part of your hormonal levels, you will experience varying amounts of "breast growth spurts".

Follow is a timeline to explain breast growth in transgendered women:

3-6 Months continuous HRT

By this point you should be experiencing tenderness, tingles, and itchy skin around your nipple area. A small bud should begin to develop under your nipple at the 6 month point.

7-12 Months continuous HRT

By this point you will have obvious buds beneath your nipples, and will be experiencing quite a bit of tenderness in same area. Growth in this period is very intense, in terms of the body building the tissue which will eventually expand to make the shape of the breast cup.

13-24 Months continuous HRT

Within this timeframe, you will experience sporadic periods of growth, and non-growth, and by the end of this point in the timeline, you should have developed, at the very least, an A cup breast. You should still be experiencing tenderness, and discomfort in the breast area, but be reassured that this is good, and means your breasts are growing.

25-48 Months continuous HRT

By this point you will know if your breasts have completed their growth cycle, or if they continue to growth. If by this point you are still experiencing discomfort, and pain, and the buds beneath your nipples are still hard, then they have not completed the growth cycle. If they have expanded, and began to fill the larger area of your breast, then your cycle has completed.

49 Months and Beyond

At this point, you should have fully developed, or near fully developed breasts. You may notice a fluctuation in size, depending on weight gain,and loss, and your breasts "tissue" still may continue to grow, and expand.

I hope this helps to give you an outlook into what to expect of breast growth. Of course, as I previously emphasized, we are all different, and will each of us develop uniquely.

Much Love, Lea