How will I know if I miscarried at 19 weeks pregnant?

i'm 19 weeks pregnant and I haven't felt the baby move at all yet, I thought I felt a few flutters around 16-17 weeks but haven't felt anything sense, I had a doctor appointment last week and the heartbeat was strong and they said she was very active. I've just been feeling weird, no bleeding or serious cramping, just random little pains here and there, I'm just hoping someone can possibly say something to ease my mind a little bit, I was thinking about buying a fetal heart monitor just to make sure. Is it normal to feel these things at 19 weeks?