Cassa said..Still only small bubbles

, even with the glycerine,
Fail
Fail

First, the right washing liquid makes a huge difference.
What are you using to make the bubbles? Not an ordinary bubble blower, I hope. You need to get two thick pieces, of dowel, about 1cm thick and 30 cm long, then make a loop of absorbent rope about 1m in diameter, and attach it to the two pieces of dowel. Then bring the dowels together, dip the rope ring in the liquid, lift it out and separate the dowels to make a big loop, and then 'sweep' the loop of rope around to draw out a big bubble. Then bring the ends of the dowel together to close the bubble. Atmospheric conditions also make a significant difference for really large bubbles. Early in the morning on a humid day works best, with little to no breeze.
Here's the idea. I like to stand with a light breeze behind me and just lift the sticks in the air and walk backwards slowly.