The report says there is a mass, but that either they have low suspicion it's a problem, or that they think the risk of it being a serious problem is low.
Ask your doctor for clarification, sweetheart. There is simply no set medical meaning for the phrase "low suspicion." Don't just read the reports and stew, tell them that everything they send you is frightening and nobody is explaining what it means, and insist someone talk to you about what they say.
I'm sorry you have had this happen. I had my first mammogram (long time ago) and had a BiRad of 5. BiRad of 6 is supposed to be undoubtedly cancer. Boy, was I scared. With a BiRad of 4, they will probably do with you what they did with which is fast track you into a breast surgeon/oncologist. Don't be afraid. It's the best place to be for this. My breast doctor took great care of me. I had a choice to make which was needle biopsy or full biopsy. I had something a little different than you with calcifications that had several issues with them that each made it a more suspicious of cancer case. I chose the needle biopsy and it was not cancer. They removed the calcifications. I've not yet had an issue wince and that's been many years ago now. That they wrote low suspicion is great but you must follow up. Call your doctor office and get a referral to a breast doctor and push to get seen as quickly as possible. Sometimes with a mammogram that is abnormal, they will do either a 3D mammo or a breast ultrasound but think with a BiRad of 4, they are going to likely be more aggressive. Let us know what happens.