Without sounding presumptuous, it appears that you may have some issues that require professional guidance and or advice. With saying that, i'm not judging your issues/concerns at all. I only say this because when you say, "i don't really have emotions." that suggests to me that you never developed a proper emotional awareness or, perhaps you have but it was skewered by traumatic or problematic childhood/adolescence. You say that you recognize when you have, "negative" thoughts such as homicide. I think it's natural for most anyone to experience fantasies of homicide ( this, however, is just me and i'm not a therapist ) especially given our culture. Considering the types of media that we're surrounded and relieved by, i think it's only natural to think of these scenarios. an example may be...,watching a T.V show about serial killers. It's only natural to imagine how one might do the same actions. Many people make a living off of these fantasies, whether it be fiction writers, comedians, etc..,
If you recognize these thoughts as being wrong and feel they're wrong then i don't think you have anything to worry about. However, if you recognize these thoughts but don't think they're wrong only because it's what society decrees as wrong then you may want to speak to someone about them. Either way, the fact that you recognize that you have a problem with how you're thinking shows that you have a conscious because you do ultimately care about what you do and what you think.