Hi I M 5 Ft 45kg 25year Old Healthy Girl.i

Hi I m 5 ft 45kg 25year old healthy girl.i have no health issue...I m lean but only problem is my breast which us bigger n heavier in size due to which I have back ache...plus it is embrassing....my periods are regular....no health ussue none in my family have such problem...Ihave to wera 32 size d cup bra....please tell me reason n possible treatment for same