A bridge with one load cell and two resistors will only work if the resistors are exactly the same.
You might have to select them with a DMM.
Indeed better to use two (or four) load cells if you can pull that off mechanically.
Mind the polarity. With added weight, one side of the bridge has to increase and the other has to decrease voltage.
Leo…
A 4-wire load cell is just two 3-wire load cells in one.
Measure the resistance between the wires of your 3-wire load cell.
Find the two wires with the highest resistance.
Those are the two wires for the excitation voltage (+E and -E).
The remaining one is the load cell "output", that goes to +A (-A for the second cell).
So...
Connect the first laod cell to +E, -E, and +A.
Connect the second cell to +E, -E, and -A.
This only works if the two load cells get opposite forces.
If the two load cells get both the same force (e.g. when both mounted on the same side of a platter),
then swap +E and -E of ONE load cell.
Leo..