Any time you have sexual relations, it must be a completed act of intercourse. I am not sure what you are asking, but if you are asking about sterilization or contraception these are immoral. They are sins against God and the Sixth Commandment.
A couple who has a serious reason to space/avoid children can do so through abstaining. How much you abstain may depend upon your circumstances, but most couples can abstain periodically by using natural family planning.
I suggest you contact your diocesan family life office about classes on natural family planning (NFP) if you feel you have a serious reason to avoid further children at this point.
Your wife is probably fairly close to menopause, so NFP may be a short term solution.