Attempting NFP


So we have 2 kids and feel that we are done. But hubby doesn't want to use condoms - and I have some breast cancer in the family, so I don't want to go on the pill. Anyone here tried to just natural family planning? Did it work? Or was it really hard? We don't have sex super often - like once a week if we are lucky - so feel like temporary abstinence is no big deal. But I definitely DO NOT want to get pregnant again. Any advice is much appreciated?