I'm going to take the usual questions one by one:
1. Why shouldn't we use the birth control pill? First of all, there are many health reasons to not use it. The pill greatly raises the risk for heart attack, stroke, thrombosis and breast cancer and not just if you are older. Since the advent of the pill, even the so called "safe" low dose pill, we have seen heart disease and strokes in women in their 20's and 30's! Secondly, the way the pill works is that it prevents a fertilized egg from implanting. Yes, it does stop ovulation but not all the time. The woman on the pill ovulates LESS, she does NOT stop ovulating totally. About 25% of the time, her eggs DO get fertilized and if this happens, the pill prevents the new conception from implanting in the womb. Instead it passes into the toilet and dies. This IS abortion because what was passed into the toilet was genetically a total new human being! That's why they call the pill an abortifacient!
2. Why shouldn't we use barriers like condoms? Again, there is the irritation factor for the woman and of course, the men feel a greatly reduced libido using these. Those are definitely the safest type of birth control but they are not all that safe. Other barriers like shields don't work but if an egg does get fertilized, the shield may be a problem. Shields can also cause irritation and raise the risk for uterine cancer etc as does any source of constant irritation internally.
OK, those are the physical reasons now let's look at the theology. We are not supposed to say "no" to God. That is, Christians believe that each life, each pregnancy, is a planned Act of God so if a life results as a repercussion of a couple making love, that is God's Plan EVEN if it creates an unplanned pregnancy to unmarried people - we do not know why God plans things that we don't understand, but we know that we cannot understand much of God's plan and/or won't until we get to Heaven.
So does the Catholic church feel that we should do as the Duggers did and have umpteen kids? No, actually the church does believe in family planning using Natural Family Planning which means abstinence for 7 days a month. That isn't very much and the rest of the time, you can proceed totally naturally. Natural Family Planning is NOT the old method of rhythm and not dependent on having regular periods - it is done by observing bodily signs "down south" in order to tell exactly when you are ovulating!
Ironically, Natural Family Planning is now known to be much more effective than the pill in preventing pregnancy - the pill is only 60% effective but Natural Family Planning is 95% effective and actually used by many who are not Catholic or even Christian!
What, you might ask then, is the difference, between Natural Family Planning and contraception? Good question. The differences are several.
First, you are not saying "NO way" to God - instead you are saying "I don't think I'm ready now" because by not doing anything artificial, you are opening the door to God overriding (I prayed that God would override my Natural Family Planning - I felt uncomfortable having another child because of a chronic illness but I knew if God overrode, it would be ok... unfortunately, God never DID override our Natural Family Planning).
Second, you are not mutilating your body or doing anything destructive to avoid pregnancy. Remember, our bodies are the "Temples of the Holy Spirit".
Third, of course, if an egg gets fertilized which we do believe is a planned Act of God, then it will get implanted and you will be blessed with another child, that is, although you let God know you don't think this is a good time for you to get pregnant, you are also saying "But Thy Will be done" that is, if He has planned another child for you, you leave the door open!
Fourth, Natural Family Planning is something done as a mutual decision of the man and the woman! Since they are a couple, this is the way things should be!
Planned Parenthood estimates that 60% of abortions are due to failed artificial birth control i.e. if you have said "NO WAY" to God and He overrides, then you might want to terminate your baby.
Planned Parenthood also says that 80% or more of Catholic women are using artificial birth control. Why is this? My feeling is, it's due to not knowing any better - that is if they knew that Natural Family Planning was not only a whole lot more effective than the pill but also, it's not defying God's Will should He want to provide another child, and if they knew how easy Natural Family Planning was to learn and how wonderful it feels, and how risky to their health the pill is (some researchers say that the two most avoidable causes of breast cancer which is in epidemic in our society now - are abortion and the pill!), few women would want to continue using the pill.
Consider learning Natural Family Planning - it's better - way better for you, it will not raise your risk for heart attack, stroke, thrombosis and breast cancer and best of all, it does not lock the door to Divine Providence! Win- win, yes?