This is a Starwood stay, correct? If so, you would receive two starpoints (from Starwood, not AMEX) for each night, for the cost of each night. For example, if one night was $150, you would receive 300 points for that night (sans any Starwood status; you would receive more according to elite level).
The points that you have already received, are the points from your AMEX card, simply for charging it.
Does this make sense?