A maternity photo shoot can be a beautiful way to document this special time in your life, but it's ultimately up to you to decide what you feel comfortable with. If you're concerned about your appearance, it might be a good idea to discuss your concerns with the photographer and see if they have any experience working with pregnant women and can help you feel more at ease.
Also, it's important to remember that these photos are not just for you, but also for your child and future generations to look back on. They can be cherished memories of your pregnancy, the time when you were carrying and growing your baby. It's all up to you and your personal preference, whether you want to do it now or after the baby is born.