I have a 4 year old and a 6year old and went through a lot of changes with my pregnancies as well. Hormones do a lot of crazy things to our bodies. Aging and hormonal fluctuations happen regardless of pregnancy though so just hang in there and take good care of your hair. It may curl it may be wavy, I've gone through rounds of both. My hair was definitely more 3B prior to having my children and now it seems I'm stuck between 2C and 3A but as I stick to the CG I notice more 3B areas coming back to life. I don't follow all the CG techniques. My basic is no heat styling, no silicones and no sulfates. I do use sulfate free cleanser once a week but otherwise just cowash. Also trying to stick to more natural products.
Remember too its not just what you put on your hair but in your body. Drink lots of water and eat more vegetables than you thought possible. Also healthy fats and proteins.