Breathable Layers. Unfortunately, there is no perfect solutio here. I would, however, try and take some advice from the world of outdoor sports. First, layer to allow for adjustments in temperatures as you go about your day. Second, choose breathable materials to allow your body to regulate heat more effectively. Finally, watch out for the extreme temperatures that can come in summer, espcially while pregnant.
Grooming & Clothing. This is not likely a question that you would go to your doctor for. Your girlfriends may have better advice than the doctor would. Perhaps the prenatal guide book or pregnancy manual your OB recommended may have some helpful hints. I would bet the sales person at your favorite store may also know the perfect solution for you.