Baby movements

Ok so I am 16 weeks 3 days today still haven't felt baby movements.. I do know from the last ultrasound and my last appointment they were looking for the heart beat she is very lazy stubborn and can't be bothered. She like to hang out by my back with her back turned.. I am worried this my 3rd they say I should feel the flutters by now. Is that true ? My next doctors appointment isn't until 10/21.