pass the career thing is hard post-baby. There is no rush to get to the next stage. It can wait, and P won't be small for long. I was on the cusp before DD. I came back, got passed over, have had S, am back, I may well be passed over again. It will happen, and while I do care and do want it, it is no longer the most important thing on my radar.
gt you are doing amazingly. I used nipple shields, neither DS or DD got any confusion. They just wanted milk! So I suggest approach with caution but don't rule out just because of what the MW says. BFing is time consuming, make sure you are comfortable. I always had 2 big pillows ( had to rugby ball hold) and had several sets of feeding pillows around the house. I never sat down to BF without them, the remote, sons water and cake. 
YW you always have such good, calm, knowledgeable advice that I always think you come across like one of the mums of several DC and am always slightly taken aback when I remember that J is your first.