I'm not sure. I would call at least because better safe than sorry. Especially if it is a vast decrease in movement. I was 38 weeks when ny son stopped moving like usual so I went in for an ultrasound and it turns out that I had oligohydramnios which means my amniotic fluid was really low. The lack of fluids was constricting his movement and he could have died if I hadn't gone in and been induced. That being said, you are only 19 weeks so it could be nothing. But it never hurts to check.
I wouldn't. I remember when i first started feeling her it wasnt everyday. I would get so scared. But they're still small. I'm sure he/she is moving around but you can't feel it. Just wait till you get further along they wont stop moving lol.