I'm with Starlight. The Coffee Frother/ Aerolatte is the way to go. Handy & portable. Loads on-line. Or inStore Sainsburys have the bodum one.
I have a large glass 3/4 fill with water then powder. Doing it other way makes it lumpy.
Shakers made it too lumpy, hand blender too Frother but Goldilocks is now a v happy girl. Think its just trial & error.
good luck