Reliability of risk assessment tools, living with stress

I have a family history of breast cancer and certain other cancers (not ovarian, and no triple-negative breast cancers).  My mom was post-menopausal, but just under 50 when she was dx with breast cancer.  We have not yet had BRCA testing (but will).

I just had the scare of my life.  I went in for a mammogram and ultrasound, and was immediately sent for a core needle biopsy because they found something on my that was a Bi-RADS 5.  I was fully expecting to hear it was cancer, but amazingly, it was a rare, benign "nothing".  The radiologist something like this in the breast is 1/100,000.

I was referred to a surgeon to have this removed and for high-risk management. I learned that my lifetime risk of BC is 30%.  I am under 40, thin, I exercise, I had 2 kids before 30, I breastfed for 2 years.   My sister, who has multiple modifiable risk factors that I don't have was given a lifetime risk of closer to 20%-25% by her doctor.  Apparently, the fact that I have had a biopsy drives up my risk according to the model, even though the thing they discovered has zero correlation with breast cancer.  My dense breast tissue is also a risk factor, even though it is completely typical for woman of my age and weight.  Does anyone ever ask about the margin of error for these models and their predictive value?  Do doctors ever discuss this?

All of my relatives who have had breast cancer have been postmenopausal and/or overweight.  10% of breast cancers are hereditary, and 40% of post-menopausal breast cancers can be attributable to modifiable risk factors. 

I have a healthy respect (and deep fear) of breast cancer.  I am meeting with a genetic counselor and will probably send my mom for testing, and I will have a PBMX and oophorectomy if recommended.  But if my test is negative, I still feel like these risk numbers still put me in the shadow of cancer.  I will still have an elevated screening protocol.  They are more likely to pick up things that are nothing because they will be doing routine MRIs on me.

I want to be careful and do what the doctors recommend, but the last several months of my life, between tests and appointments, have been nothing but anxiety.  And all they have turned up is a tiny lump that I could ignore if I chose to.  With this heightened screening protocol, I probably have many call backs and biopsies in my future.  Not a day goes by that I don't worry about breast cancer.  Stress also kills people.  I want to do what the doctors recommend, but I worry about the physiological impact of this chronic anxiety.  I never sleep before doctors appointments or tests.  I lost 15 lbs over 4 days waiting for my biopsy results.  I am at the point where I am almost wishing for a BRCA+ result so that I can just get the surgery and be done with the anxiety, but then I stop and think: wait, that's nuts!  Surgery is not a treatment for anxiety.  

I recognize that this system is designed to locate high risk individuals, screen them, catch cancers early and/or prevent them with surgery, but these models have flaws, and all this scrutiny, and the often unnecessary procedures that result, take a psychological and medical toll too. Overtreatment has a "cost" too http://www.cnn.com/2013/07/30/health/cancer-overdiagnosis-overtreatment

It sure seems like there is a lot of work going into locating the 10% of people who will get hereditary breast cancers, not nearly enough work on getting people to change their lifestyle so that they can reduce their risk from preventable causes, and not nearly enough concern about the medical and psychological toll of overtreatment.  

Can anyone relate?  My doctor says I am a "soft" case, so he is giving me options with respect to screening and surgery on my "little nothing" lump.  I feel the tug to do as much as possible in terms of screening and prevention, but I do wonder if I'm doing more harm than good.