Im actually haveing the same dilemma with #3. We just started talking about going again not really makeing a decision, but it appears my body has made the decision already (yet to confirm with HPT). My DS is only 8 months old so if i were pg then he would be around 17/18months. I suppose he would be running around and may or maynot still be BFng but im concerned i wouldnt be able to give him the attention he requires.
Now i remember rightly i felt the same way with DD before DS came. She was 3 months of turning 3 and i have to say that age was great to introduce #2 for us.
I think you need to way up the pros and cons of do you want two in nappies (thats assuming DD is not toilet trained yet), will she still be B/Fng (thats if you are), do you want them reasonably close together so they can go to school together etc, or space appart abit so the eldest is a bit more self sufficient i.e can go to toilet on her own, play happily while your feeding bub, can help with bathing bub without trying to get in to lol.
It is a hard decision but only you can truly answer, everyoned situation and needs are different.
Good luck.