Yes, the condition is called amenorrhea. It can be of two types. Primary amenorrhea is when a girl doesn’t have her periods even after the age of 15. And secondary amenorrhea is when a woman stops getting her periods for more than 4 months. Amenorrhea can happen due to reasons like failure of the ovaries, problems in the central nervous system or pituitary glands, or some issue with the reproductive organs. If a woman gets her ovaries and uterus removed then also she stops getting her periods.
At your point of pregnancy, the uterus is not very big, and it would be nearly invisible with the woman lying on her back. A lot of the muscles of the abdominal wall were stretched during the first pregnancy. These stretched muscles permit the forward flop of the uterus when standing. This forward flop makes the uterus much more noticeable.
It’s amazing how hard you, specifically, the person who wrote this question (which is at least the hundredth by you in all your sock puppets I’ve seen in the past six months), are trying to somehow make trans people look rhetorically inconsistent over matters that only you think are authoritative. The presence of balls and a penis doesn’t make you a man. The presence of a working womb doesn’t make you a woman. And only transphobes think they do.
You need to be able to explain in anatomically correct terms where your children came from. “You grew from an egg in mommy’s uterus that was fertilized by daddy’s sperm.” That is truthful and accurate. If they ask “what is sperm, and what is a uterus” tell them you will explain when they are older and better able to understand. If you cannot bring yourself to tell your children the truth, have your pediatrician break it down for them. Children do not need to be shielded from what is considered a natural process. The sooner that you can prove that they can trust the information coming from you, the safer they will be when some stranger tries to tell them otherwise. But if you have the slightest inclination to pretend your children came from immaculate conception, it would be better for you to be silent on the matter.