I'm sorry about your grandmother - that will definitely kick off HA. I had a spell of right-sided breast pain for a while. My doc told me to take evening primrose oil, which helped a lot.
From what I understand, BC lymph nodes in your armpit don't feel like a general enlargement - they feel like a palpable lump. So yes - stop poking your armpit. As for your breast, it's possible that carrying your DD on that side is irritating the muscle under it. When did you stop breastfeeding? That can also cause breast pain. Or it could be hormones. Either way, it sounds like your doc is being appropriately vigilant, but your tests aren't at all worrisome.