Breast lump changing

So I've had a lump in my left breast for quite some time... Like a few years. I was too freaked out to ask my doctor until my boyfriend found it and asked me to get it checked out. I went for an ultrasound that my doctor set up and they immediately told me it was a fibroadenoma and I was happy with that and went on my merry way.

Fast forward several months.

I can REALLY notice the lump now. Before I used to have to search for it but all the sudden I can feel it when I just lightly run my hand over my breast. I barely fill an A cup so it's actually distorting the shape of my breast and becoming the most prominent feature. It has never grown before in all the years I've had it so I'm starting to get concerned. Sometimes it feels itchy and warm in the area, but doesn't hurt. Should I ask my doctor for a biopsy to determine for sure that it's benign or wait for my next ultrasound in 2 months?

If it helps I'm 20 and was told I have dense breast tissue.