My girlfriend wants kids ASAP due to fertility issues, but I’m not ready. How do I handle this?

I (22M) have been dating my girlfriend (21F) for a while, and we’ve always had a strong, supportive relationship. We both attend the same university, and things have been great—romantic, understanding, and overall very solid. However, recently, she’s been making comments that have started to really bug me, and I feel like I’m being put in a difficult position.

For context, I’ve always liked kids and definitely want my own in the future, but my focus right now is on finishing university, getting a stable job, and setting up a secure life before bringing a child into the world. I’ve made this clear to her from the very beginning of our relationship—my plan has always been to have kids when I have my own house, car, and financial stability. She understood and agreed at the time, so I never thought it would be an issue.

But lately, she’s been dropping more and more comments about wanting kids now. She’s also mentioned before that if we ever had an accident, she wouldn’t take the morning-after pill because she “doesn’t believe in them” and thinks they would mess up her body. I respected her stance and just made sure we were always careful, so I didn’t dwell on it too much.

Then, out of nowhere, she dropped a bombshell on me. She admitted that her mom’s side of the family has an extremely low birth rate, and she’s already showing the same signs of fertility issues that her mom and aunt had (her aunt is 47 and has never been able to conceive). Because of this, she feels like time is running out for her, and she needs to start trying for kids within the next couple of years—preferably as soon as possible.

I was stunned. This was the first time she had ever mentioned this to me, and I couldn’t understand why she hadn’t brought it up earlier. I didn’t get angry or blow up at her, but I reminded her of what I had told her from the beginning—having kids at this stage of my life isn’t a simple yes-or-no decision for me. I want to be prepared, to provide for them, and to make sure we aren’t struggling from the start.

She didn’t take my response well. She started tearing up, got up, and went home. Now I feel like our entire relationship is hanging on this one issue. I love her, and she’s an amazing person, but I’m worried that if I continue standing firm on my decision, she’ll ultimately end things.

So, my question is what should I do? I really want to stick to my plan because having kids now is just not an option for me. Can anyone drop some advice?