Anatomy Scan

I feel like my anatomy scan got scheduled a little to early. I went in last week and I was 18 weeks, 4 days. It just wasn’t what I expected, everything was so small and I kinda felt like it was being rushed. I noticed when she was taking measurements of her kidneys the right one was much smaller than the left but anytime I asked if everything was okay she told me nothing seemed abnormal but she wasn’t allowed to discuss much since she isn’t my OB. My follow up appointment was the next day however my OB got called out for a delivery so a nurse got sent to review the scans with me. She didn’t actually have access to the pictures, just the notes the sonographer left. When I mentioned the kidneys she said all the sonographer wrote was the measurements of the left one an that was it. She didn’t put anything under abnormalities yet they want me to go back on the 30th (I’ll be 22 weeks, an 3 days) for another sono to check her kidney growth an also check her heart one more time since it was so small. I’m just worried and a little frustrated, how can nothing be abnormal yet the kidneys are to different sizes... so I guess I was wondering if maybe any other mommas have had something similar happen to you?