Back again: found a lump

I am back again after years of 'breast peace'. In 2018, I was diagnosed with a fibroadenoma in de left breast after a mammogram/US/biopsy due to increased family risk. I also had a breast MRI at the time. My mother had BC at the age of 48. I am now 46. I have been followed-up with 6 months ultrasounds and 12 month mammograms since then. The last ones were done in April 2021 and everything was clear at the time. Only some benign cysts and some duct ectasia. I was rated BIRADS 2. Next follow-up was scheduled in September 2022.

Since the whole 'breast topic' is very frightening to me I do not self-exam my breast so I do not know my breasts very well. However, last weekend I decided to be brave and started feeling my breasts. Under the areola of my right nipple I felt a small lump. Problem is that I do not know whether it has been there before or not. It is round and smooth, bit like a pea, but feels different than the rest of the tissue. Problem is that I do not have a point of comparison. It might be there for years and just be part of the normal. I decided to go to the GP. She could only find the lump when I showed her. Based on how it feels, she thinks it might very well be a cyst or a fibroadenoma but she thinks that we need to be sure and has therefore referred me for an ultrasound which I will have on November 9th.

Meanwhile, I start to panic. What if they missed something on the previous US/mammograms? What if this is a cancer that was not visible on images from April and now already is palpable? If so, what's the point of the whole screening thing which my breast surgeon explained to me like 'trying to catch the very early symptoms before it is actually cancer"?

I am perhaps jumping to conclusions but I guess I am simply scared.