I don't have any experience of this aspect of breast cancer but will echo what @SoldierCrab has said, please make sure you explore options thoroughly before making such a major decision. Speak to the professionals and talk to a counsellor who is experienced with cancer issues. It may very well be the best decision for you but it is a major, no-going-back one. I, for one, would have found it very hard to have not been able to have children - I didn't have mine until my late 30s and early 40s. However, amongst my childless friends, I have one who made the decision in her early 30s (not cancer-related) to have a tubes tied because she got tired of boyfriends who thought she wasn't serious about not having children. She is turning 60 this year and has never regretted that decision as she knew she didn't want them. In fact, as I've gone through the child-bearing years I have discovered that as many of my friends have remained childless as have had kids. Just not something that I would have wanted if I could have avoided it.
Please also remember that we pass on many different genes to our children, some good and some bad. I don't know whether I have the BRCA gene and unless the test is free for me, I probably won't know. I do know that treatments and screening are improving all the time and gene or not, my daughters and my son, will have a higher awareness of the possibility of breast cancer from my experience and their knowledge of my sister having had it. I'm as aware of having passed on the propensity to mental health conditions that abound in my extended family and I knew about those before I considered having children - I just try to monitor my kids and make sure they are aware of things.
I guess all that I'm saying, @Cynth6 is, talk to the professionals, read the literature, seek others experiences as you are doing, then look into your heart and weigh up the pros and cons. Whatever decision you make has to be one you own and be carefully thought out. I'm not a virtual huggy type person but I'm sending one out to you.