Alright, let's say all those stats put out by non-Catholic sources are lying and NFP is only 75% effective as the Dept. of HHS claims. Of course that absurdly lowball claim is based on 25% of women who practice NFP get pregnant while not mentioning that indeed women practicing NFP are generally a bit more open to children than those using contraception and might want to get pregnant. 

Let's just say NFP is THAT ineffective (which it isn't). Who cares? Engage the heart of the matter. I certainly appreciate the difficulty of your particular situation. The suffering of choosing between abstaining and the consequences of a highly dangerous pregnancy is so real. Still, it is in such moments that the choice between selfishness and the self-offering of Jesus becomes most present. On which side does contraception fall?