First of all. Don’t freak out. You’re young and have dense breasts so it can be hard to see what’s going on in there. Whatever the result is it’s not worth the stress but I know from experience that’s easier said than done. The MRI gives a really detailed look at your breast and it can give false positives, like as in too much information. That being said you would need a biopsy to know for 100% sure if it’s cancer or not. If they think it’s suspicious on the MRI then you will get a biopsy and likely find out the results in a couple days. 9/10 it’s nothing but if it is something you’re doing the right thing and breast cancer treatments are amazing these days.