I 30M am getting cold feet about moving in/cohabiting with 29F after previously agreeing to doing so. Is it okay to delay things?

I've been dating my GF for a little over a year (we met in September 2023) - a few months back we talked about her eventually moving into my place in February when her lease ends. At the time, I wasn't 100% there but i was 60/40; however, I felt that by February I could get there. We said we’d discuss more when the time came.

When finalizing things a few weeks ago, she expressed concern that I wasn't enthusiastic about her moving in. I expressed to her that I had some reservations, but I also had some excitement. I was more ready for the move but still had some trepidation that i thought were just nerves; however, my feelings have since continued to accelerate to being more nervous/unsure about all of this. after the fact, she mentioned that if were to pull back from moving in she would "probably break up with me" which definitely didn't put me at ease.

we've spent the last week apart spending Christmas with our respective families this year, and i've had more to time reflect on the situation - I don't feel 100% enthusiastic about the prospect of her moving in - especially as the date nears. I feel that I am rushing into something that might complicate things for us in the long run. Sure theres a little excitement there, but mostly it's 80% angst/dread/nervousness about the entire situation. Even telling other people she is moving in - I feel a pit in my stomach. I feel even more pressure because of her expectations on marriage/kids etc (our timelines are misaligned a bit).

I'm thinking about telling her tomorrow when I see her that I am not ready for this, but I feel like a piece of shit given that she has given move out notice to her landlord (which means she would need to find another place or go back to her landlord and work something out) and has been telling everyone. I know she's going to be very upset and the last thing I want to do is her hurt - but I do worry that jumping into this without a solid understanding of where the relationship ultimately will go/ not have a strong foundation will only do both of us a disservice.

How should one be thinking about all of this? Is this just nerves/anxiety? Or should i consider delaying this? How do I message this?

TLDR: Girlfriend planning + committed to move in with me, I’m getting cold feed now and unsure how to proceed

UPDATE: i spoke to her as soon as i saw her in person. it was a very emotional conversation on both sides. she was upset, but understanding on how i felt. our first step is pausing the moving and subsequently reassessing the relationship - what that looks like i’m not sure of but very much glad i spoke to her and thank you for the c