A lump where you're describing is most likely the result of an ingrown hair or else a sebaceous cyst, which is the result of a blocked oil gland (which also arises at the base of a hair follicle).
In either case, it's common, benign, and nothing to worry about.
Breast cancer is mostly a condition that women get when they're older. Although it's possible to get breast cancer at age 25, it's pretty rare.
As long as your lump is in the skin and not under the skin, it's not a lymph node, and has nothing to do with breast cancer. If it's in the skin, it will move as you move the skin. Best wishes.
Dimpled skin over the breast can be concerning. Dimpled skin in the armpit is not unusual.
An infected ingrown hair could cause the glands to swell, but those glands are under the skin and not in the skin.