Speak with a priest about your reasons for desiring to limit the possibility of birth (via natural rhythms only). Better still, phone your diocesan offices and ask for contact details for a moral theologian (priest if possible).
It is very important, I think, that couples prior to marriage understand fully what The Church does state about birth control (by Natural Rhythms method only and only in serious reasons circumstances). And that they both fully agree with what The Church has to state and prior to celebrating The Sacrament of Marriage.
The article below from EWTN is quite lengthy but worth a read for those concerned about limiting the number of children and birth control. Certainly, here in Australia, there are means of being educated in how the Natural Rhythm method works and for Catholics, it is the ONLY means of controlling births and for serious reasons only. I don’t think one should presume that one has serious reasons, but to speak to a priest or better still a moral theologian about one’s moral position and what one thinks are or might be sufficient serious reasons. In that way, conscience should not trouble one. If diocesan offices only have contact details for a lay person who is a moral theologian, I think one can be relatively assured that diocesan offices has confidence in that person.
One can also contact their diocesan offices and ask for contact details to be educated about the Natural Rhythm method and in the context of Catholic Teaching.
Read above link. "
WHAT METHODS OF BIRTH REGULATION ARE MORALLY ACCEPTABLE?
“If there are serious reasons to space out births, reasons which derive
from the physical or psychological conditions of husband and wife, or from
external conditions, the Church teaches that it is morally permissible to
take into account the natural rhythms of human fertility and to have
coitus only during the infertile times in order to regulate conception
without offending the moral principles which have been recalled earlier”
(Humanae Vitae, 16).
Thus, the same teaching of the Church which condemns the use of the
unnatural methods of birth control explicitly approves of the use of
Natural Family Planning when there is a sufficient reason to avoid or
postpone pregnancy. With its emphasis on the necessity of a serious reason
to use even the natural methods, the Church is warning against selfishness
in family planning. "