Maternity clothes ?!

Autumn
I'm almost 7 weeks along and I am so uncomfortable! I don't think I've gotten any bigger, but it seems like my stomach is so much more sensitive. Im a bigger person to begin with so maybe that's why? 
My question is when Is it okay to start wearing maternity clothes? Or should I just start with the waistband thing? This is my first pregnancy and I'm kind of lost.