Should I break off the engagement if we have different timelines for marriage and kids?

I (28M) recently proposed to my girlfriend (23F), and she said yes. We have been together 3 years and 2 months and we love each other deeply. When I proposed, she said she wants to spend her life with me. However, she seems hesitant about actually getting married soon. She keeps saying she wants to "take one step at a time" and "enjoy each stage with me'" which makes me feel like she’s not ready for marriage as soon as I’d like.

But me — I want to be married sooner rather than later and start trying for kids ASAP. I wouldn’t want to wait more than 1–1.5 years before starting a family. Even that sounds like a compromise for me, because ideally I would have already started having babies. She also wants children, but she says she doesn’t want to rush before she's more ready.

I’m worried that our different timelines might be a serious issue. I don’t want to spend years waiting when I already know what I want. Yet I really want to start a family with her.

Should I break off the engagement, or is this something we can work through? Have any of you been in a similar situation? How did it turn out?