Why do my boobs hurt when i'm not wearing a bra? i'm a size b so it's not like they're that heavy. should i worry?

Do not worry: Many women feel more comfortable with support (bra) regardless of breast size. You may have a condition like fibrocystic breasts in which breast tenderness is more common. Does the soreness change with your menstrual cycle? If so it may be related to ovulation, possible PMS, etc....You need a breast exam to be more specific than this. Good wishes.