With any of the anti-abortion sites, you need to fact check. For example, many will actually claim development happens faster then it actually does, or attribute emotion or thought process to a fetus before the brain has developed enough to actually have them. Some even try to scare women by saying abortions can make you infertile, while in reality safe abortions do not - the risk is lower then if you were to actually give birth. Also, abortion being illegal won't stop abortions, just safe ones. If you want people who are pro-choice to listen to you, you have to do more then spout whatever you find on pro-life websites. Try to develop an argument that promotes other choices, explain how unnecessary abortion is for reasons of finances or social stigma by finding resources for low income families or single moms. List studies that show women who have suffered depression, break down, or needed therapy after aborting. Discuss the rates of couples who have an abortion and then break up because of the stress/emotional after effects. If all you do is repeat the not always true dogma on most pro-life websites, people aren't going to listen who are pro-choice. A little lie or misinformation in your data will make people tune it out. Too much "dear mommy, why, I already love your voice" emotionalism will make people tune it out. Go for facts, go for truths, and go for the impact it can have on women and their lives, and how much alternative option there is now.
- ps, regarding "the silent scream" - its one video of a fetus to young to have developed a brain. Its not evidence, its a propaganda video. "We have this ultrasound that makes it look horrendous! We will use it!" Many people believe it to be a hoax. This is the kind of thing that will make a lot of pro-choicers just tune you out - its over the top, its not conclusive, it seems fake.