103 calcs for stall speed allow you use a CLmax of 2.0 if you have 50%+ flaps. At 450 lbs and a CL = 2.0 you need 115 ft2 of wing. You're not FAR off, but with a CL of 2.0 and only 100 ft^2 your stall is at just under 30 mph. One thing to consider though, is the stall speed in part 103 is for a 170 lb pilot not for gross weight with fat pilots and safety chutes.