It is common for pregnant women to start feeling fetal movements between 18-25 weeks, so not feeling any movement at 18 weeks is generally not a cause for concern. Every pregnancy is different, and some women may feel movements earlier or later than others. As for the size of your belly, it can vary depending on factors such as your body shape, baby's position, and muscle tone. If you are worried about the lack of movement or the size of your belly, it is always best to consult with your healthcare provider who can provide personalized advice based on your specific situation. They may recommend further tests or ultrasounds to ensure everything is progressing normally. Remember that every pregnancy is unique, and if you have any concerns or questions, it's important to reach out to your healthcare provider for guidance and reassurance.