First you'll need to make sure the closet flange is secured to the floor. Since you are probably on a slab, you may need to anchor the flange to the floor by drilling the concrete floor and setting anchors. Once you get the closet flange secure, install a new wax ring and secure the toilet with closet flange bolts.
If the toilet doesn't leak when you flush it, there's a chance you aren't getting any sewer gasses in the room, but unless you fix it, it will only get worse.
Not sure how much "somewhat" is, but it should not move at all. Check the bolts on the bowl base to insure they are tight. Since it has been moving, I would suggest pulling the toilet up and replacing the wax seal. At this time you can make sure the flange is not broken or able to move.
If you have never made a mistake, you haven't done much.