18 weeks - no movement, should I be concerned?

Hi all! I’m 27F expecting my first. Im 18w3d as per LMP but if corrected to baby’s growth I am 19 weeks now. I haven’t felt any movement at all. I have a week until my 20 weeks scan, haven’t had a scan since our 12 weeks + 13 weeks NHS scans ( ended up with two as baby didn’t want to move/cooperate for measurements) because we are in the process of buying our first house and wanted to save money where we could.

I received some comments at a baby shower I attended last week ‘has the baby not moved yet?’. I usually don’t care what others say but I’m starting to feel worried that I haven’t felt anything. I have had cramps here and there and abdominal pain but I am quite gassy and suffer from indigestion so pretty sure anything I have felt is just gas. Even the ultrasound technician at 12 weeks told me she could see from the scan I was very gassy.

I did get to hear the heartbeat at 16 weeks ( I had a student midwife present at my appointment who did it) which did reassure me but I can’t help but feel worried. What does movement feel like and when did you start feeling baby?