Feeling movement?

When did you start to feel baby actually move? Not just flutters but strong movement? 
I'm 21 weeks and rarely feel movement of such. 
In the evening when I'm laying in bed I can feel baby wriggle a bit, but during the day I will only feel one or two nudges and that's it. 
It also happened quite strongly when I was drinking a cup of tea. 
You can't feel it on the outside at all or see it. 
When did everyone start to feel baby become really active?