If it is your first baby you may not notice and might just think it is gas.
Im 18 weeks also and the only time i feel my baby move is when im laying down it feels more of a fluttering feel not so strong
Yup my doctor told me I wouldn't feel my little one until atleast week 20 but I felt her at 18 only when I was laying flat on my back!
Its normal. Try laying on your back very still stretched out some that may help and drink cold orange juice like 20 minutes before. But even if you don't deep anything you still are early a lot of women don't feel anything until 20-24 weeks