Baby is still really small.it could be moving you just can't feel it because of its size and where its laying
The baby is still small at 20weeks sometimes it moves without us feeling it because it's so gentle
You're fine everyone is different I barely feel him, mostly I feel him wiggle while I'm laying down
I'm sure you're fine. Try drinking orange juice or eat something really cold. Your baby could just be towards your back and babies sleep about 80% of the day. If you're extremely worried I'd head to the doctor just to ease your mind!