Even from her perspective, she is not going to believe you.

She is going to believe that you think it on the moment, but she's just going to see it as a reaction from her getting engaged. And that's not what she wants anyway. Even if deep down she would want it to work with you, she doesn't want to risk it all for you when it seems like it's an emotional response to her getting engaged. Because then you could change your mind 4 months later as abruptly. It doesn't sound "safe".

I don't know Taylor, but I assume she is around your age so around 35. This is the time lot of people (and mostly women) decide it's time to settle if they want to start a family. And even if everyone would love to settle with the love of their life, it often isn't the case. But the next best thing is to find a loving partner, that provides stability and security, that will be a good loving parent. If she found that, she isn't going to blow everything to risk it with you, because yes you are a risk, and her time is a limited resource.

I had a similar experience, and when she said she wanted to stop, and I learnt she met a "safe" guy to settle with, I tried to show her I was ready. She told me I should have done this before, and basically she can't be sure if I'm being truthful or if I'm just like that as a reaction. And to her that was too big of a risk, she couldn't lose more time when she is getting older and wants a family.