Have there been other early/sudden deaths in your family? Could certainly be familial aortic aneurysm, of which I am unfortunately quite familiar. If there were a history of sudden death of a parent, sibling, or blood-related aunt/uncle, you have a stronger case for immediate surgery.
In the case of the person I know with this condition, his surgeon gave him an option of when to have it surgically repaired. I had suggested he wait a few months and get another scan to see how fast it was growing, which was the absolute worst advice for him (funny, because he never takes my advice any other time...)
He spent the watchful waiting time acting like he was dead. In the end we decided he should get the surgery because he was so paralyzed with fear his would rupture and he would die, just like his dad did. He needed the surgery not to live, but for his peace of mind and quality of life.
You need to do what feels right for you, and find a doctor who will support your decision unless you are being ridiculously and unreasonably demanding. I'm not clear if your aneurysm is currently at 6cm and I am NOT a doctor nor am I giving medical advice. But you need to advocate for yourself. If the doctor can't convince you with hard facts and validated statistics, then you should doctor-shop if that is what YOU need to feel comfortable and go on with your life.
Just my opinion. Good luck to you.