Ms. Sophia,
I’m sorry I was tired last night and you deserve the best answer I can give. So if life begins at the moment of conception then abortion at any point in the process becomes a sin. I think we are all clear on that.
Contraceptives are a second part though. I also had some difficulty understanding why when I first returned to faith more seriously, but after learning more the doctrine is pretty logically sound. Forgive me I’m not a priest or theologian but I’ll translate what I know as best I can. The issue with contraception is two parts. Firstly the way many contraceptives work is they either block a fertilized egg from implanting in the uterine wall, or make your body believe that it is pregnant, which causes the uterine wall to shed, discarding any conceived eggs. In both cases conceived children could be lost. I’m sure there is more but those are two of the issues with them.
The second part with contraceptives is that the sexual act is supposed to be both unitive to a married couple, but also open to life. If God decides that life isn’t appropriate at that time then that is His prerogative. But we can’t intervene to physically stop it. I’m certain there is more to it than just this, and perhaps others could add where needed, but those are some of the clearer arguments. So the Catholic doctrine is clear on these types of issues. All the best, praying for you as well.
Servant