Lumpectomy vs. mastectomy, pregnancy impacting treatment choices

Hi - i am recently diagnosed, and also learned i’m pregnant at the same time, now finishing my first trimester. Spoke to all doctors and still unsure of my choices. I understood from my surgeon that 1) i can have a lumpectomy following radiation (if based on MRI, things look good / clear). however, i wasn’t able to get MRI scheduled due to pregnancy and also radiation doctor told me i would need to wait till after i deliver. This introduces a lag to treatment which increases risk in ways that doctor couldn’t quantify. Them also told me that if i have need to have chemo, then it’s not going to be lag as radiation would follow that and will take time. 2) I understood that my chemo plan is TBD because we would need to know if lymph node has been impacted / there’s a bigger spread. I understood we won’t know for sure until surgery; 3) i can go through a mastectomy which MIGHT eliminate need for radiology (assuming lymph node is clear). Overall, mastectomy doesn’t seem to deliver materially better treatment outcomes relative to lumpectomy (might be a small lift). For the context, my cancer is likely hereditary - i am 40 and my mom was diagnosed in early 40s. My genetic testing report came out as negative / no mutations found.  Based on what i know today, i’m leaning towards mastectomy simply because 1) it seems like i have a higher genetic risk despite what generic report states and 2) i don’t want to delay radiation treatment and put myself through more risk. Having said that, i might just end up loosing a breast for no gain - still having to do chemo, radiation and also not have a breast. It’s also a bigger surgery which is higher risk given pregnancy.  I would much appreciate any advice and blind spots that i’m missing.

Such impossible choices , often the case going through this process , you are making decisions based on so many uncertainties. If your gut is telling you that there may be a genetic element to this ( there are most definitely genetic connections not yet established ) would mastectomy be the best option for you to give you peace of mind in the future  ? 
Im sorry you are going through this at what should be a really joyful time in your life . Hopefully someone who’s had similar choices to make will be along soon to share their experiences . Best of luck whatever pathway you chose .Lots of support here .Best wishes Jill x