Well, that's why things are going well, at least for now. You're providing a stable environment and allowing your corals to adapt to it. One thing to keep in mind that a lot of people overlook - as your tank fills with corals, they become part of your filtration. I'm not going to suggest you run out and bring in a hundred corals all at once, but if you can maintain good water parameters and steadily add corals to your system you may actually be able to increase your bioload beyond what you think is possible with your filtration.
But slow and steady! As you add corals, your demand for alk/ca will increase. If you have a slow ramp-up of coral life, then you can make adjustments, like dosing to replenish necessary elements in between water changes. If you add a lot of corals all at once, the sudden increase in alk demand can strip your water and lead to rapid declines.
The most important thing is to maintain a stable environment so that the corals can adapt to it and grow accordingly.