I am ttc and someone adviced I had conceive if my husband stops sucking my breast. How reliable is this school of thought?

It is not. Presence of prolactin and lactation (milk for baby) prevent pregnancy- not oxytocin (feel good hormone, orgasm and contraction in breast to let milk down). Husband allowed. Doctors' orders. Now if you are lactating, or finished nursing the baby but husband decides he would like to continue where baby left off & he continues to nurse, then almost impossible to get pregnant.