If you’re not already taking Magnesium, I’d suggest that instead of a laxative. It has a gentle laxative effective at about 500mg daily. Massive doses are used for colonoscopy prep, so obviously it’s not dangerous 
But Mg is an essential electrolyte - which are needed in far greater amounts when you’re restricting carbs.
Great to hear about your sense of well being and healthy sleep. These are perhaps the most important telltale signs that what you’re doing is working.
As for how much weight you’re losing versus your expectations, I would imagine that it’s your expectations that are out of whack … your body usually knows best (after all, it’s the expert).