How annoying for you! Spotting in the early weeks while bfing is usually associated with starting the mini-pill but you haven't mentioned this so I will guess that you are not taking it. In that case, it is possible that it is AF, but it would make you unlucky! It is earlier than most women get AF back. It well could be an isolated bit of spotting, but until you are sure I would be careful about DTD without contraception.