You may not have had time to get familiar with your camera, and the "feel" of different lengths on your zoom lens, as you are still within the 30-day return window. Take your camera and "zoom in" all the way with your kit lens (to 55mm). Do this outside, pointed at a bird or squirrel-sized target 30 feet away in the yard. Now back it up to 34mm. It will feel VERY short. That is the amount of "free" telephoto you have with a crop body, and which you lose with a FF.
Now, look at the price of good f/2.8 telephoto Canon lenses. $7,000.00 or $13,000.00 is about the neighborhood. You would need that kind of lens JUST to regain the length lost by dumping the crop body for FF if you want to keep the wide bright 2.8 aperature. Telephotos aren't even cheap if you go with a smaller aperature. This may not seem alarming unless you have an above-average level of interest in squirrels or other distant small-ish things, but you do constantly find other situations where you will wish you could zoom in more, and certainly not less, I promise.
And this effect is even more noticable at 200mm than it is at 55mm. I bought a 1.4x tele-extender to screw onto my 1.6x crop body for use with my 70-200mm lens. And that is just about enough zoom to shoot a groundhog (which is the size of a large housecat) from a distance that feels comfortable to me (and to the groundhog). And the tele-extender robs you of a full stop of light, so your 2.8 lens becomes an f/4 lens.
If you do go FF, consider seriously keeping the crop body for longer shots. With the kind of money involved, a $600 or $800 extra body is small potatoes.