Fiberdanomas???

I have had a lump in my left breast for almost 10 years. It was discovered when I was 18 and pregnant with my first daughter. At the time, they did an ultrasound and told my it was a cyst and could be left alone. After the birth of our 3rd daughter last April, my doctor decided he wanted to ultrasound it himself... Came back telling me that it was a fiberdanoma and still nothing to worry about. This week my pcm on base (military) decided to check it out one more time. This time via ultrasound they found 3 lumps in the left breast. They are telling me that one looks "cystic" and fluid filled, the other 2 have characteristics of fiberdanomas but that they are referring me to a surgon who can decide what needs to happen. One of the potential "fiberdanomas" in under all my breast tissue and that is the one that is concerning me the most. I am 27 years old. Wife and mother of 3 little girls. My mother dies at age 36 from Melanoma and I am so scared. Would it be unusual to have that many lumps in one breast? What about a fiberdanoma under breast tissue?  My doctor told me not to work myself up because they wont know anything until they either take them out or do a needle biopsy... but I am so scared... The one that I have had for so long changes size... seems to get bigger and smaller during different times of the month. I am on birth control pills. They can sometimes be tender... Any ideas or advise?