I gave a target figure for my salary during a call (say $X) and the company comes back with $Y (5~10% less than $X) plus a small bonus and stock options. When adding the bonus to $Y, it actually comes to be about $X; although the bonus is an "up to so and so percent of salary" so while there's no way to know for sure, it would probably come to about $X if we assume the bonus to be the higher end of that range. When I originally gave my target salary figure, I was taking things like stock options and other benefits into account; obviously I could only estimate what my benefits would be since I didn't know beforehand but I tried best to think of the whole package I would get when coming up with the $X.
Now that I have more details on what the entire package is going to be and having done rough calculations on my expenses against it, I'm hoping that I can negotiate about an extra 3%~5% from the salary they offered me. My concern is though, that by making a counter offer, I may seem greedy (maybe the employer thinks "the salary we offered plus the bonus is about as much or even slightly more than the figure you gave us. plus there's stocks too. so why are you asking for more now?"). And additionally, by making a counteroffer that isn't very high in amount, I'm afraid that it may give the impression I'm trying milk the cow as much as I can, just to see if I can score some extra cash. While I don't want to jeopardize this offer, I also want to avoid the regret of not having negotiated at all. Is there such a thing as a candidate responding with a counter offer that is too low?
p.s. if it does seem like I'm trying to milk the cash, please do be direct and point it out. I'm still learning the various etiquettes involved in an employer-employee relationship so perhaps I'm asking a question whose answer is obvious to everyone.