Baby kicks?

I'm about 13 weeks along according to my LMP and I'm expecting my first baby. I still have not had an ultrasound or even been in to hear the heartbeat due to scheduling issues with my doctor (don't get started on how frustrated I am about it!) Anyway, I have a coworker who is also around 13 weeks and expecting her first child and she told me she and her husband already can feel the baby moving. This has me worried. I've been concentrating on trying to feel any movement down there with no luck. Should I be worried??