Movement (17 weeks)

Between 13 and 16 weeks I was feeling lots of movement, so much some nights I could sleep from the rolling and fluttering, just before 17 weeks I feel it has just stopped/is barely noticeable. I can assure you what I felt before was definitely not gas, I felt movement very early with my first and even have videos of him kicking at 18 weeks. I am so so nervous something has went wrong. I feel my bump isn’t that big either? I have a scan on Saturday and I’m not even excited for it, I’m so so anxious that they will give me bad news.

Is there any explanation for this? Am I over thinking?