Any Advice/Help Would Be Great....

I am blessed to be 17 weeks pregnant with my second child. There are times where I don't feel pregnant and I'm not sure that I've felt baby move. My doctor is not worried and said sometimes women don't feel movement until later on and not to worry because everything looks normal. 
Last appointment it took a while to find the heartbeat and it was in the 140's when the baby was found.
I guess I'm just scared and nervous
I don't remember anything but the last few weeks of my first pregnacy, so I can't really compare there. I've also been feeling some twinges and things here and there. Anyone else going through or have gone through the same or similar thing?