ADH, high risk, and a bunch of questions

I'm 42. My mother had BC (lumpectomy, radiation at age 47, premenopausal), father's mother had BC in her 80s, didn't tell doctor for 2 years about lump, by then it was coming out of her skin, and had mastectomy but it was already in her bones, died 2 years later). I've been getting mammograms since 35.  I had BRCA testing last year - negative. I made sure that I had my first child before I was 30 and breastfed each child for about a year. I tried to do everything to reduce my risk.  I had my last mammogram in October 2009. Then in May, I started having these "let-down" feelings in my right breast multiple times a day. After a few weeks, felt around and there was a lump. DH confirmed. Saw the doctor. Got mammogram (which was excruciating, never had any discomfort before) and ultrasound of that breast only - doctor requested both, but I was in so much pain that I didn't push for them to do the other one. Then biopsy which showed radial scar. BS wanted to take the whole thing out. 2 weeks ago had lumpectomy and had ADH (pathology: proliferative fibrocystic mastopath, radial sclerosing lesion with florid sclerosing adenosis with microcalcifications, florid ductal hyperplasia and papillomatosis with focus of ADH, duct estasia with columnar cell change and cysts). BS is recommending Tamoxifen and increased monitoring. The lump was 4cm x 4.5cm, which seems like it must have grown pretty fast if they hadn't seen anything last October on my mammogram. So I've looked at Tamoxifen and I'm not thrilled with the potential side effects. I eat very healthy (I'm gluten, dairy, soy, corn free so I don't eat any "prepared" foods except potato chips), but I also have chronic lyme w/ joint/back pain and a nerve condition where I can't wear any restrictive clothing without back spasms. So I haven't worn a bra in about 8 years. Luckily I'm an A cup so it hasn't really mattered. So there's cornstarch and lactose in Tamoxifen so if I did take that for 5 years I'd be having diarrhea, back spasms, nightmares, increased anxiety, etc. (my food reactions to those) aside from any regular side effects that the doctor mentioned. The BS thinks it's overkill to think of a prophylactic mastectomy but I'm terrified and I don't feel like Tamoxifen is an option for me. These last 3 months of ultrasounds, biopsies, lumpectomy have been absolutely riddled with anxiety. My youngest is 5yo. And when my mother had her BC, she had a lump in one and the cancer was in the other. So now I'm worrying that since they didn't do the mammogram on the other one, that they missed something important. So the BS wants me to see an oncologist and a plastic surgeon to learn about my options. I guess I just want some commiseration. I've looked at several threads about ADH and prophylactic mastectomy and everyone seems to be all over the map in terms of what they do. I feel almost paralyzed with anxiety and I'm not normally like this. I feel like it's taken over my life.