Benign cysts from ultrasound / do I need a biopsy?

Hi everyone - thanks for taking the time to read this post and for letting me know your thoughts. I will try to make this quick --

I am 35 and last year my nurse practitioner found a lump in my right breast during my annual exam. I went for an ultrasound and the radiologist found 2 cysts that were benign. This year my nurse practitioner felt the lumps again and sent me for another ultrasound just to be sure it wasn't anything to worry about. The ultrasound came back that there are 4 cysts that present as benign in my right breast, and my left breast has 2 cysts that are also benign. Last year they did not check my left breast when I did the ultrasound but I went to a different place this year. They asked if I had any pain in my breasts and I said that I had had some pain recently but I attributed it to my small dog walking all over my breasts when I am in bed. I kept him off of me for a week and the pain subsided.

My question is -- should I ask for a biopsy to be sure that the cysts are benign, or should I trust that the ultrasound is a good method to detect a benign cyst? I am slightly concerned because the cysts seem to have increased in numbers over a year and have not subsided as the dr said they probably would. Is there anything else you would recommend that I do to monitor the cysts? My breasts are quite small (I barely fit an A cup) and I have never had a mammogram

I do not have a lot of family history with breast cancer but my father's mother's sister was diagnosed when she was 40 and did not survive.

Thanks to all and I wish you all the best in your pursuit of health! xo