Suddenly I feel that the strangeness between the closest people makes me very uncomfortable and chilling ... What do you think of this problem?

If there is less contact between people, there will be barriers. No matter your biological parents or brothers and sisters, as long as you haven't been in contact with them for a long time, you will feel strange. Your situation is that your mother lives with you and your sister doesn't live with you? As the saying goes, big brother is like father, big sister is like mother, and you are big sister. Don't share common sense with her. She may also be inseparable from the child. This should be the case between relatives, whether they are husband and wife or brothers and sisters, otherwise the feelings will become weaker and weaker and there will be nothing to say. Think about whether this is true or not. Maybe you are pregnant and your body has changed. You often think about this! Don't think so much, just talk. I wish you happiness every day.