Me too. I am a bigger girl though so I think that doesn't help. I went to the EPU I was so worried about lack of movement (3 previous losses have made me paranoid!) And the midwife told me it's not likely I would feel anything till after 21 weeks. I am nearly 22 weeks and I'm just starting to feel some flutters.
Don't worry, everyone is different. I know on here I found that everyone seemed to feel movement early and that's what got me a bit worried but it's quite normal I believe not to feel anything at 18 weeks.
Oh, I also have an anterior placenta that was picked up at my 21 week scan so I think that delays when you feel movement too. So maybe that could delay movement for you too.
Try not to worry. Xx