I don't know about anyone else, but when I was pregnant I hated it when people touched my belly, supposedly for luck

It could be that your girl is one of those that says, go away, I'm fine, you don't need to keep checking :-) If you are worried at all the first port of call should always be the vet. If it's moral support you need then you are in the right place :-D
Is this her first pregnancy? And yours? :-D
Edited to add: Oops! Just reread and noticed you said it was your first time. We all worry if things are going well, every time, so you aren't alone. Do you have a copy of 'The Book of the Bitch'? I read it several times when my girl was in whelp and it helped with some of the questions.