By the way, if by using contraceptives you mean your husband uses condoms and insists on using them though you disagree because you know its a sin I don’t think you are culpable in a such a situation. Only your husband would be. I’m not sure that in itself would be a bar to conversion.
**1735 Imputability and responsibility for an action can be diminished or even nullified by ignorance, inadvertence, duress, fear, habit, inordinate attachments, and other psychological or social factors. **
If your husband is truly forcing you to use contraceptives, you probably fall under 1735 and have an exemption from mortal sin, owing to duress or social factors, whichever you want to call it – you don’t have freedom in the matter.
If you discussed your problem with a priest, I wouldn’t bet a dime that he’d refer to 1735, to even inquire about your problem. I think you have to interpret 1735 yourself, honestly, and leave the rest to the mercy of God (which is what 1735 is all about).
Now, this is not just me talking. Listen to Pope St. John Paul II in section 18 of his encyclical THE GOSPEL OF LIFE (Evangelium Vitae):
[Now, this encyclical is about abortion, euthanasia, and the death penalty, but he includes contraception into the discussion, in the preceding section. ] ***Decisions that go against life sometimes arise from difficult or even tragic situations of profound suffering, loneliness, a total lack of economic prospects, depression and anxiety about the future. Such circumstances can mitigate even to a notable degree subjective responsibility and the consequent culpability fo those who make these choices which in themselves are evil.
So, the use of contraception is objectively evil, but under your circumstances of duress (pressure from your husband) you should not consider yourself ineligible for the sacraments. Here, in this post, is the Catechism of the Catholic Church and a sainted Pope telling you about the mercy of God. You should not neglect it, but even use the grace of the sacraments to pray for your husband and your situation.
I think you should not only attend Mass, but become a Catholic and receive the sacraments. Jesus said we must not be ashamed to confess our faith in him. A lot of Catholics around these forums will argue with what I said. But, they cannot show me or you another encyclical from a pope or a paragraph of the catechism which overturns when I quoted above – you will find that they don’t like what the catechism says (yawn).