Hi Jenjams
I know exactly how you're feeling. I felt a few tiny flutters at 16 weeks and then nothing for ages and I was worried. It's just that stage where the morning sickness is over (hopefully), you're feeling well and not quite showing enough to put your mind at ease.
I'm now 22 weeks and feel my bubba all the time, so don't stress I'm sure everything is fine, it's probably still a little early for you to feel anything!
Take care
xxx