I'm not saying your thesis is wrong (I think it is, but can't be sure), only that you have some factual issues.

Margaret Sanger was a Republican pre-Civil Rights Act, the time when Democrats were the party of racism.

I don't know if Sanger was a racist, but she did say:

“I admire the courage of a government that takes a stand on sterilization of the unfit and second, my admiration is subject to the interpretation of the word ‘unfit.’ If by ‘unfit’ is meant the physical or mental defects of a human being, that is an admirable gesture, but if ‘unfit’ refers to races or religions, then that is another matter, which I frankly deplore.”

You write: "According to the U.S. Census, white people will become a minority by the year 2045. So while our numbers are going up, their numbers are going down — they’re terrified of that."

It's true the U.S. will soon become majority minority, and it's true white people are terrified. It's also true the census indicates the Black population is increasing, and has increased as a percentage of the overall population since the passage of Roe v. Wade. But it's a slight increase. The percent decrease in the white population is mostly due to an increase in the Latino population.

Personally, I think that birth control and abortion are a net positive for everybody of all races. Countries with lower birth rates have more women's rights and lower poverty levels. Choosing when to have children produces better health and wealth outcomes for women and their children.

Again, not saying you're wrong, only that the facts you're presenting are incorrect.