I fantasize about murdering others am I a psychopath?

I constantly have thoughts of killing other people, and not with guns it is always with a knife or another sharp object. The thing I am worried about is that when I imagine killing another person it makes me feel happy and I am scared that I might actually act on those thoughts one day. These thoughts are of both people I know and people I don't. When I have these thoughts I feel no remorse for my imaginary victim. Most of the time when I have the urge to kill someone my rational thought snaps me out of it by forcing me to think about the consequences of my actions. I don't want to kill people but it's like my subconscious does! Any help would be great...