Check your calculations. I get 1.92*10^30 kg.ok, so if my equation to find the mass of the sun is:
T²/R³ = 4п²/GM
and i used the orbital period (T²)(in seconds) and the distance from the sun (R³)(in metres) of say, venus, then i transform the equation to find "M" and i get:
M = 4π²(R³/T²) / G
M = (4π²)(1.08e+11/1.95e+7) / (6.67e-11)
but the mass of the sun is 1.98e+30.