Is the dent small enough that you can try shrinking it with a torch at this point?

Are you trying to finish it with no body filler? Unless your a pro you might have to settle for getting it as close as you can and let the minor imperfections slide. I wouldn't get too upset with a small 1/16" low spot, especially if this is your first attempt at this kind of work.

Also you shouldn't be swinging the hammer with any real force. The weight of the tool is enough to do the job, especially the pick end.