What could it be?

am 23yrs i have feeling that i want 2throw uo but am not preganant and my brests r geeting bigger but one of them is bigger than the other one and has discharge but this discharge is clear and i went to 2 doctors and they make check but just with thier hands and they said to me they can not find any thing not normal in my but i have went to another doctor and she also said the same but she siad ot me i have to make ultra sound to see what is the reason of this discharge and am really worried cus i have no idea what could it be espaciall some time i have itching in one brest in some time also in the other one.what could it be,thanx?