Your mom seems to be such a kind, supportive and encouraging person. I think she's just proud of your how much you've managed to lose. In my opinion, going from 24 to 12 is an amazing progress and it's surely noticeable. I don't think you'll be disappointing anyone, they'll all admire your new figure
Your mom seems awesome and has every right to brag about you
Going from a 24 to a 12 is amazing and you WILL look tiny to everyone, trust me! That's a big difference and everyone will be comparing the new you to the "old" you.
I did the same thing, went back to visit where I used to live after losing a significant amount of weight. I also wasn't technically thin yet, but honestly, it was better that people had been warned You've watched yourself shrink over months - these people will suddenly be confronted with a very different version of you, and will be surprised!