I wouldn't assume that your positions will change on this matter. This isn't like "you haven't tried this food, so how do you know?" This is something that's been thought about, and a preference has evolved.

Love is not enough in a relationship. You really have to have compatible life goals. One example I often use is children: If one person wants children, and the other doesn't, someone is going to be unhappy no matter what happens.

But even if you agree on children, there are lots of details. You've encountered one: Adoption versus having your own biological kids. You can also get into issues on how to raise kids, like what forms of discipline to use, whether they should have an allowance, and so on.

You may want to talk more about your views on what married life would be like, and what raising kids through to college (and beyond) would be like. It may be that you'd find some other differences that would give you a clearer idea on whether the relationship would work or not. For instance, you may agree on everything else, but then find that your partner believes children should move out at age 18, get a job, and pay for rent and stuff, and that saving money for college is wrong (the kid should pay their own way). If you don't hold that view, there is probably no way to reconcile these differences.