I need some answers

Hello all, I've got a serious thought clouding my mind. You see, I gave birth to the most amazing and beautiful bouncing baby boy I've ever known in the month of September 2017. All is good in the hood with my little man. The thing is, I had protected intercourse with my SO about 2 months ago, and the condom broke. I am breast feeding, and my periods are irregular. What I'm really trying to ask here is if there are any symptoms you get for pregnancy while breastfeeding? I've been nauseous every day for about a week now with no reason. My back constantly aches. and I've been a bit moody. Can anyone help me out here?