How old are you? You speak about your mom, so I am guessing you are still in high school? It is common for high school and college aged girls(in their twenties) breasts to grow. your mom thought you were pregnant, so must still be young if you are child bearing age. Nothing amazing about your growing breasts. It is natural for your breasts to grow at your age.
Also, if you are no longer a vegetarian and you are eating more meat based protein like you said you are then your breasts will grow. Vegetarians don't normally have large breasts because they don't eat meat(that is why your's were small), but since you are eating meat and more protein then they will grow. It is common what is happening to you and your breasts.