It is common for pregnant women to start feeling their baby's movements between 16-25 weeks of pregnancy. However, the frequency and intensity of fetal movements can vary. At 18 weeks and 4 days, it is possible that you may not feel consistent movements yet. Factors such as the position of the baby, placenta placement, and individual differences in sensitivity can affect when you feel movement. If you are concerned about the lack of movement, it is always best to consult your healthcare provider for reassurance and guidance. They may recommend monitoring techniques or additional tests to ensure the well-being of your baby.