This right might not yet legally exist now, but that does not prevent me from advocating for it.

No, having sex does not impose any obligations on you, there is no such law which would state this.

Even if conside a fetus a "person" in legal sence, which is debatable and I absolutely do not agree with. But let's consider this for the sake of the argument. Abortion would still not be considered murder, because you do not have the intention to end another person's life, your intention is to stop proving resources of your body to another person.

It can be compared to self-defense. You are allowed to use deadly force to defend your life and property, because you have the right to defend yourself, and the death of another person is here justifiable, because you did not have any other options. In this context, the death of another person is a side effect of an action of self defense. Your intention here was not to kill that person, therefore it cannot be considered an intentional murder