It is completely normal for some women to not notice the linea negra line or experience changes to their belly button at this stage of pregnancy. Every woman's body is different, and these changes can vary from person to person. The linea negra line typically appears later in pregnancy, usually around the second trimester or early third trimester. As for the belly button, it may start protruding or "popping out" as your uterus grows and puts pressure on your abdomen. However, not all women will experience this change, and it may happen at different times for each individual. Remember that every pregnancy is unique, so there's no need to worry if you haven't seen these changes yet. If you have any concerns about your pregnancy or want more personalized information, it's always best to consult with your healthcare provider.