Baby movements...

I am pregnant with my 2nd child and I will be 16 weeks on tuesday. I keep reading on here that a lot of people have already felt their baby move at this point especially if this is their 2nd or 3rd baby. I haven't felt anything...or I don't think so at least. Should I be worried? I haven't had any cramping, bleeding, etc. I'm just worried something is wrong. I go to the Dr for an ultrasound on February 2nd to find out the sex of the baby. Should I just wait until then or go in earlier to make sure everything is ok. I'm just worried because we tried for almost 2 years to get pregnant again. Any words of wisdom is greatly appreciated :-)