Congratulations Arianna, at 4 months is when my breasts really kicked in with a case of the itchy, aching, puffy, tingling, sore, tender boobs.
I kept track of my nipple and areolae size, at 13+ months my nipples went from 1/4" to 3/8" and my areolae went from 1 1/4" to 2".
Those dimensions changed off and on, especially when puffy and swollen.
Hugs and smiles, Jessica