Liz, this is a topic close to my heart. My mum has had a breast cancer removed and I have had a pre-cancerous lump removed. You should definitely be checking throughout pg and bfing, although it will be more difficult. The advantage though is that you should also be more familiar with your breasts so changes should be easier to notice. TBH I am slack in this area too, but I do also have regular ultrasounds (and mammograms when not bfing or pg) and checks by my breast surgeon. Still, I should be more vigilant, you'd think I'd know better.