Slow riding's hard for us all, don't think you're alone in this.
I've been riding for 25 years and still have some moments at low speeds!!
Essentially riding a bike is about controlling centrifugal forces, one from each wheel and one from the engine.
The best trick is to keep some revs on... not excessively so, but enough for the engine to generate a centrifugal force... about 2500-3000 rpm should do the trick.
This will help keep the bike upright for you.
Then as you rightly say, it's all clutch control and rear brake.
I guess it's all practice-practice-practice to master it.
Keep trying and you'll get there