Breast lump?

Katie

Question for parents of little girls.. my daughter is 17 months and she’s always had a little hard bump in her breasts from birth and now the left breast is completely flat but her right breast still has a hard bump in it. Naturally as a first time mom I’m panicking I called her doctor and she didn’t seem concerned and said it will most likely go away. I was just wondering if anyone ever experienced something like this . TIA