I had my top surgery in the winter. The surgeon bound my chest and had a drain that needed emptying every couple hours on each side. Two days after the surgery, I went out for a walk that turned in to a three mile hike. I think I was just trying to prove to myself that i was a tough guy. No problems came from the walk, and i was walking through snow. My surgeon probably would have had a fit if he knew and I wouldn't recommend doing it, but the point is that some activity after the top surgery probably won't cause a problem.
Surgeons are pretty careful about making sure that there aren't any bleeders and usually give post op directions.
If you don't feel pain, don't worry about it. Soft tissue surgery that doesn't involve entering a body cavity is usually not horribly painful. Although the Dr. may prescribe pain medication, often times you can get away with over the counter pain meds, but ask your Dr. if its ok first. Things like Aspirin should be avoided because they can make bleeding more likely.
Having any surgery is a stress on the body and the psyche. Is it possible that some of your anxiety is coming from the fact that you have made a major change to your body? Even though its something you wanted, its still a change and a step from thinking about not having breasts to actually not having breasts.
If you need support, by all means put it into the forum. Try to keep good thoughts and enjoy your new freedom. This summer, you will be able to go out without a shirt on for the first time!
sam1234