Worrying..

I can’t help but worry. Im a first time mom and I’m 20 weeks and 3 days with an anterior placenta, and still haven’t felt baby yet.. I thought I was feeling him because I would get these random pulses in my stomach but today’s the 3rd day I haven’t felt any yet... and I went to this 4d ultrasound place at 19 weeks and 4 days and the US tech told me I was measuring at 18 weeks and 2-3 days or something... (i forgot the exact days) I have an appt with my ob tomorrow at 3 but I still worry and cant help but give myself anxiety ...