Laura - I first felt movement (wouldn't call them kicks though) at about 14 weeks. Felt the movements for a couple of weeks and then didn't feel anything really for a couple of weeks after that. For me it seemed normal. Then the first real "kick" came at around 18-19 weeks. I think even after that I could go a day or two without feeling much. There is still plenty of room in there and if you've been busy yesterday and today you might have missed it.

I agree with the others though - try the cold drink, OJ, something with sugar etc and lie down.
If that doesn't work, I'd get an appt tomorrow to get checked. There's no point worrying until Wed.

Hope bubs has just had a quiet couple of days in there