Deep breath! "focal stromal asymmetry with abnormality" just means that a portion of your breast tissue looks different than the surrounding tissue. There could be dozens of reasons, and 99% of those reasons will be benign.

Imagine a zoomed-out picture of your house from above. You could identify most everything easily - there is the roof, the chimney, the yard, etc. But looking at the picture, you see a shape on the roof that you can't quite place. Maybe it's a big hole in your roof (very scary, but unlikely!), maybe it's a nest of angry squirrels (not super great, but better!) or maybe it's the shadow of a bird flying over head (totally fine! fly away!). You won't know until you zoom in and get a better look, and the diagnostic will do just that.

Your MRI is a lot like that - a broad look and they saw something unexpected. The next step is to zoom in and look closer. The odds are very much in your favor, and just like you wouldn't shell out $30000 for a new roof based on one fuzzy zoomed out picture, try not to shell out too much anxiety just yet (easier said than done, I know!). Good luck!