It's definitely my experience too.
6 kids and pregnant with my 7th.
I have become disillusioned about NFP and am seriously considering a tubal ligation after this baby is born.
I have many health problems and am exhausted and cranky.
I'm having a hard time believing it is the will of God to have more kids than we can care for.
Prayers for you and your husband. May your faith be strengthened.
Please don't do that. Have you consulted with CCLI or another solid NFP teaching establishment about your NFP practice?