I'm 24 weeks pregnant and find dresses, maxi skirts and leggings to be most comfortable. There's specific maternity jeans, but they don't feel that great over your bump as you grow. Just basically anything that's loose or very stretchy. You find you feel hotter when you're pregnant too, so something not too warm also
Congratulations - I think comfort and room for expansion are probably your bywords - Depends where you are but you will probably be heavily pregnant during the warmer months so dresses may be favoured option - I bet you google will have loads of links, you have plenty of time to check out pregnancy forums for tips and maternity fashion sites.