Here’s some things to consider:
Depending on the growth rate, no change in 6 months doesn't mean it’s not cancerous. In general, low grade breast cancer grows from one cell to a size seen on a mammogram in 9 years, intermediate rate is 6 years, high grade is 4 years. So if its currently slow growing there wouldn't be much/any change in 6 months.

I had intermediate grade DCIS, pea size. It was missed on the diagnostic mammogram and ultrasound, thought to be a weird lymph node. Very embarrassing for the radiologist because her report said no cancer and that it was consistent with an area she saw on my prior two annual mammograms. She had to add an addendum to her report after the biopsy. My lesion had very little calcification, which is what the mammogram IDs best. In 4 1/2 months it had not changed size (scan to surgery).

My understanding is that when a lesion gets to be 12 mm, 1.2 cm, most oncologists will recommend surgery. A pea size is about 8-10 mm. Early treatment is simpler, and hopefully avoids the lesion becoming invasive.

I was able to have my biopsy locally, but I chose to have treatment at a comprehensive cancer center 190 miles away. I usually do followups in one day, 3 1/2 hours there and back. It gives me peace of mind to know the quality of care is high. In early 2022 the recommendation was surgery (for me), now many oncologists are recommending hormone therapy only for early breast cancer.

I am currently on hormone therapy, tamoxifen. This past year my thyroid tests were indicating possibly hypothyroidism. The doctor told me that if I went on levothyroxine they would just adjust the dose to accommodate any issues that might be a problem, and to not worry.

I am allergic to gadolinium, the MRI contrast. But I only got a red rash on my face the first time. I now take Benadryl before the scan, its on my chart. It sounds like your reaction is more involved, though.

I don't mean to minimize your issues. The difficulty with traveling, the uncertain lesion, the other health issues. It’s a lot!!
You’ll find many compassionate women on this site that understand what you’re going through. Best wishes as you work through what is best for you!