Some thoughts:
**Oral sex is wrong ** as the mouth is a Holy portal through which Our life giving Lord has chosen as the entry point to His Temple, our body. Our life giving food and water also enters here.
Therefore I believe the mouth should be kept holy and used only for life giving purposes. Not for potentially life taking uses such as the Dragon of Revelations waits for the issue of the womb that it might be gobbled up. I believe the mouth has a special role as it is stated that a man will be judged for every word that he has uttered. (No mention, that I know of, for every act,)
**Not your sin if you protest first. **
I cannot give the source but I believe it is Biblical, (someone, feel free to help here.), that states that if a woman is raped in the country side far from help the sin is not hers, but if she is raped within yelling distance of help, in the city, she shares the blame.
Contra means contrary or opposed to, ception means life giving,
Contraception means contary to life. Something must die! To allow the sperm to die is contrary to allowing life to flourish and therefore is a sin. The commandment Thou Shalt not kill, does not have a list of exceptions attached including one which says unless my husband makes me!
Just my thoughts for what they are worth.