Telling mom about my pregnancy :)

So, I am 5+5 weeks now and me and my husband haven't told anyone yet (except blasting it on here of course lol). The thing is my mom is visiting us on New Years and I want to tell her then. But she can't know till midnight :) Anyway, what are the chances of me still not showing at 10 weeks? I am pretty small framed too (5'7" and 128 pounds) so I am afraid it will show more in me and it won't be a suprise(