What are some red flags to look for in the second trimester?

I'm currently 19 weeks. I got a scan at 15 weeks and now I have to wait until December 10th for my next scan. I have had a miscarriage so obviously I have anxiety about every little thing. At my last scan Heart beat was good and nothing seemed to raise concern for them. I haven't felt her move much at all, if I am being honest I haven't really had any pregnancy symptoms besides peeing a lot and occasional cramping. I have a five year old son so it's been a long time since I have had a full term pregnancy.