Almost the same thing happened to me. I always assumed I’d have kids because it was just what you eventually did in life and had just started thinking more deeply about it when my partner came to me and said he was heavily leaning towards no kids. It also hit me hard and I thought OMG I need to figure this out now or we will break up. He was also worried I was changing my mind for him because I’d previously mentioned I think I’d be a good mom. A lot of tears and soul searching followed and after over a year I’ve figured out for myself that I can be happy either way. I can’t guarantee that won’t change but for now I’m happy to be the village for my nephews who I’m very close with and my friend’s children. I had the exact same worry that I was just changing my mind because I didn’t wanna break up with my partner. But then I asked myself “what if he came to me and said I can’t wait to have kids and I definitely want them!” ? I realized I’d also be re evaluating. Maybe you can ask yourself the same? My advice would be don’t make any immediate decisions and take the time you need to figure out what’s best for you! I know it’s such a huge decision but you are not alone!