I absolutely agree with your points of the value of life, marriage and abortion, I'm sure we'd all agree on those aspects. I just think there's maybe a little mist if you don't mind me saying, when it comes to the issue of sex as it is quite taboo in many Christian circles and for good reason if we are trying to be appropriate however between adults, it's an extremely important aspect of the marriage. Sex or making love should be a regular, initmate encounter between married couples with God even saying it should be regular, In that each couple need to make their own decisions on the frequency as well as the birth control.
I think in this day and age, many can't afford more than two kids, having more would actually be unfair to the children if you can't financially support them so a method of contraception is a very wise opinion indeed so the regular sexual encounters can continue.
Not disputing your position, just some thoughts...