Conceiving after giving birth.

4 weeks ago I gave birth to a beautiful baby girl, my husband and I have agreed to start trying again for another baby, however. I have read mixed reviews about fertility whilst breast feeding. Some sources are saying you cannot conceive whilst breast feeding and i have also read that this is the most fertile time. Any of you conceived quickly after giving birth..any tips and experiences? (It took us a little while to conceive prior to this baby and also had one miscarriage)