Do I, personally, think so? Is that really relevant? After all, what matters is not my personal predilections but what the law of the Church provides.
Notwithstanding that I am, as I have been most charitably told, an idiot, as I read things, if a married couple intentionally has sex during the infertile periods (and, by implication, not during the other periods) in order to avoid having children, then yes, that is a venial sin because they are acting with so-called “contraceptive intent.”
Whoever told you this is in error. This is the normal, morally inoffensive practice of NFP. It is not a sin either to have intercourse with one's spouse during an infertile period, nor to abstain from intercourse in a fertile period. Neither of these actions is morally objectionable. Neither one singly, nor both together, would constitute contraception.
I ma not sure exactly what is meant by a "contraceptive intent". Possibly it means a refusal of children by married couples who are inveterately luxury-loving and self-serving. If it's a question of (A) $2853 per night for a suite at a luxury resort, a month out of every year, --- or (B) baby --- and the couple goes for "A" every time, there could well be sin involved. But if they ensured their childlessness by NFP, it would not be a sin of contraception.
Maybe avarice and gluttony (these are 2 of the 7 deadly sins) --- but not contraception.