Hermione,
You must be one worn out girl.
I read and enjoy many of your posts and threads, but I have definitely noticed a recent trend focusing on the sinfulness of this, that and anything.
If I were you, I would focus less on theology and more on spirituality. Get to know and LOVE God. Let yourself surrender to Him and fall deeply, madly in love with Him. Out of that love will come your reverence and ability to serve Him. You will also notice, perhaps, some progress being made in your scrupulosity. I would suspect that if you keep looking for ways in which to sin, or catch yourself sinning, you will soon be extremely burned out on Catholicism and jeopardize your faith.
As for NFP, you are allowed to have a JUST reason to use NFP. Not “grave,” not “legitimate,” not any other word but JUST. There has to be a just reason behind choosing to abstain. However, that reason is between you, your husband and God. Typically, the faithful interpret just reasons as falling into one or more of three categories: emotional, physical or financial reasons.
Since you are not yet married, and still yet years away from walking down the aisle, you cannot begin to even contemplate what will or will not be a just reason for your situation. Since projecting possible issues seems to cause you anxiety, I would cease wondering until the next four years have passed and it is a more relevant concern. You are a brand-new Catholic and in four years time, you may make exceptional progress in some of your issues with scrupulosity, depression, anxiety, OCD, etc. and therefore not need to consider health reasons as being even a consideration in choosing to abstain.
I really reccommend you read “Life-giving Love” by Kimberly Hahn. It is a beautifully written book that speaks so authentically and sincerely about marital love and married life. She even speaks about how important it is to learn to live as husband and wife and how important it is to learn how to chart, as possible “just” reasons to abstain as newlyweds. Aside from that, she delves into the beauty of the Church’s teachings regarding God’s design for marriage.
Do you think God expects your future children to have a miserable mother? No. He wants you to serve Him with joy. If that means you are at full capactiy with 2 or 3 children, then so be it. But don’t project into the future, just live in the moment and enjy being engaged, being a student and seeking to serve Him and TO LOVE Him with all of your heart.
Also, recognize that EACH MONTH of your marriage will mean a new discussion with your husband and a new opportunity to embrace the opportunity to be a co-creator with God and make a new soul. What works for one month may not work for another month, but you will discern that with your spouse, using an informd conscience, and with much prayer.
Abby