thing:
From the POH for our 152
Ah, that would explain it. You've used the POH figure for the empty weight. I can guarantee you that the actual empty weight figure on your particular aircraft's weight schedule will be in excess of 1080 lbs. Most 152s are at least 1170-1180 lbs empty weight. So that will knock around 100lbs off your usable load. You'd then be struggling with two adults each over 78kgs - a moderate weight for middle-aged males these days.
NS