Hello and welcome to the forum. We are so glad you are a survivor and are here to support you. We thank you for your question. Following up as soon as possible is essential here. As you know, anything caught early has a better chance at a successful outcome. Did you have breast cancer cells removed from the left breast or calcification? The higher the birads number the more suspicious the findings. But that does not equate to a cancer diagnosis. A birad of 6 is most likely cancer. So, please don't worry before you have to. Easier said than done, I know. It could be scarring or calcifications triggering the birads score. There is a chance of cancer with a birads of 4, about 20 to 30 percent turn out to cancer. Focus on how many do not though. https://www.healthline.com/health/birads-score#takeaway There area many benign causes of a hypoechoic finding.
When are you next seeing the breast surgeon? Are you scheduling a biopsy?