While breastfeeding does delay the return of fertility, it doesn't stop it. I nursed each of my 7 kids for 3 yrs, and had them approx. 2 yrs apart. This is a naturally healthy spacing - part of God's great design for humankind. Please don't go against nature in your attempts to conceive again, it will happen in God's good time. Tandem nursing is such a pleasure, you'll be glad you didn't stop! I really wouldn't have wanted to have them any closer anyway!
Fertility will return, in spite of continued nursing when:
1. baby sleeps throughout the night
2. takes a pacifier or sucks thumb
3. starts eating table food
In short, anything that decreases the amount of suckling time. And, you can ovulate and conceive w/o having any periods between babies. I did this several times.
BTW, nursing through labor really is better than any epidural! I had one labor that started while I was nursing my toddler. It consisted of 3 (yes, only 3!) ctx, 20 mins apart. then a pushing urge, so I detached my still nursing toddler, sat her in front of a bowl of cereal between ctx I went to the toilet, pushed, my water broke, (which is when I finally realized I was in labor!)and then proceeded to push out a 9 lb 11 oz girl! Without a tear, hemorrhage, anything! it was one of my easiest labors!