Diagnosed with Fibroadenoma

Hi everyone. I am new to the forum just looking for some advise. I am 23 and found a small hard lump in my right breast 4 months ago. I was referred to the breast clinic which I attended today. I initially was asked some questions and physical examination carried out. I was told the lump was well defined and measured 1cm by 2cm. I explained to the doctor my strong family history of breast and cervical cancer, he suggested possible genetic testing and said he will send me for an ultrasound/biopsy and ? A mammogram however he would have to check with his senior doctor. I then went back to the waiting area and was called for my ultrasound which took around 2 mins, the radiologist told me this was fibrosis tissue and nothing suspicious therefore a biopsy was not required. I was then seen by the initial doctor who confirmed this was a fibroadenoma and no further treatment follow up is required. I asked again about the genetic testing and was advised to visit my gp for this. I feel extremely relieved! But just wondering if an ultrasound can 100% diagnose a fibroadenoma? And do patients normally get followed up? The doctor said this should go away in a few weeks to a few months, would you recommend visiting my Gp again in a few months if lump is still there or is this normal? Thanks very much.