What exercises are you doing with them? Just interested.
When I started with KB 12kg was my first, You soon gain strength and I got 16kg, and so on.
I still use the lighter KB for warming up, or sometimes in a pyramid fashion working up the weights and back down with a movement.
Kettlebells lend to slightly different movements to dumb bells.
Some KB exercises require leaning new techniques specific to KB really.
Two that come to mind first are the KB swing and the KB snatch.
I have used KB in a circuit type method with good effect. Pick four movements, work through them 30 seconds on, 15 seconds rest. Once completed all four have 1minute test. Repeat 3,4 or maybe 5 times. Work and rest times can vary depending on level of fitness.
Here’s a good website for similar https://kettlebellsworkouts.com/beginners-kettlebell-exercises-with-workouts/
As mention earlier I’m following a KB program from a book called Enter the kettlebell. The same author wrote Simple and sinister, which is a popular KB program. Really only involves swings and Turkish Get Ups with some progressive overload.
I’m boring and don’t mind these programs which are repetitive. Others prefer to KB flows, KB sport, or KB juggling!