If he is unwilling to abstain during fertile times, the only licit option FOR YOU is for him to agree to use a condom. Obviously if he is unwilling to abstain, he does not leave himself a licit option unless you simply decide you no longer want or need to avoid.
The church teaches that as long as you make clear you do not agree with his use of the condom and do so periodically, you are not culpable for his sin of contraception. This is different from withdrawal or oral sex because your giving of self to him is unaltered in the condom example, but not unaltered with the other two options. It can be confusing, especially the short version by someone who doesn’t know it so well.
We will continue to pray for you and your husband. Praise God for your new understanding of sexuality and desire to have a chaste relationship with your husband!
It will be touchy suggesting this to him without feeling like you are recommending a sinful course of action. Just keep in mind (and let him know as well) that since your conscience has told you that what you’re doing during fertile times is wrong, you have an obligation to bind yourself to the message you get from your conscience.
“Billy-bob, I know we disagree about our limits during fertile times since we are no longer using the pill, but I am growing more and more uncomfortable with what is going on between us. I pray daily for a chaste and holy relationship with you, and I can’t continue this in good conscience. I understand your doubts and confusion, but I need something to change.”
Then do your best to let him bring up the condom option, saying, “The condom will be your decision. I believe it is immoral for us to use it, but all I can offer to you is myself. What you’re willing to give me is up to you.”
Also please know that the Church allows great latitude in how far a couple can go even when they don’t intend to complete the act. A pamplet on just that came with my NFP materials.
It’s not for the faint of heart!

(or for the people who struggle with pure thoughts)