Nothing wrong with what you've done so far, but there are consequences, some of which you may not be aware of, yet.
Every time a dorf takes a step, he's utilizing a
pathfinding method. It's expensive, in terms of CPU, FPS, etc.
The larger you make the fort, and the more animals, visitors, invaders, and dwarves you have, this starts to add up in a profoundly negative way.
Especially after you breach each cavern, which can add quite a lot of entities that just love to pathfind their way around.
My first tip would be:
Keep your fort as small as possible. Use one central staircase. Build vertically, into the ground, almost exclusively. Only dig out what you absolutely need, and once you're done with an area (it's mined out) wall it off to prevent pathfinding from "looking" there. And doors help, too, especially those that are shut tightly to prevent vermin and animals from getting through them.
Second tip:
Designate a meeting area. Your dorfs will be there unless there is something for them to do. That is the one thing I think most people generally don't do, and they end up with their dwarves wandering all over the map doing whatever. Not ideal. Once you've designated a meeting area, then you can build the fort around that, presuming unless they're sleeping or performing a task, they're in the meeting area. Then you can place workshops and stockpiles in proximity to the meeting area, vertically. Less than 10-20 steps, and they can do what they need to do. Same goes for bedrooms. A far cry from 100-200 steps before they even get near the task area, which is common in starting fortresses.
Third tip:
Try to get by without animals, if possible. Farming is extremely effective (almost overpowered) and animals, comparatively, offer very little (maybe cheese?
) except, again, more pathfinding load.
Similarly, try to get by without breaching the caverns, if possible.
Fourth tip:
Get used to using the aquifer as a well source. As in, build your water well(s) on top of the aquifer. Once you do that, your fresh water needs are addressed. Despite there being some negative consequences for no alcohol, it's not as dire as you might imagine. I've run forts on only water to drink (when no Brewable material was around) for many many in-game years, without issue.
Defense is a whole other topic, but a single doorway on or from the surface, with a well armed, fully armored, and ~constantly training military guarding that door? Extremely effective.
Of course, overall, you can do what you like, and fun is obviously the goal with any game. These tips are there to keep the game in a state of high performance, if that should become an issue for you.