Current across Wien bridge
You need to redo your process, these are the steps for analyzing an RLC circuit, note that this kind of analysis is only valid for circuits in a "Steady State", this means that the circuit is on a state where it has had enough time to stabilize, hence the mane "Steady State Circuit Analysis".

Step 1: Convert your circuit into phasor domain.


  XC = 1/(j * omega * c).
  
  omega = 2*pi*f.



Vin = (Vin &lt; theta)
XR1 = 22k Ω = (22k &lt; 0º)
XR2 = 3k Ω = (3k &lt; 0º)
XR3 = 11k Ω = (11k &lt; 0º)
XR4 = 1k Ω = (1k &lt; 0º)
XC1 = - j97.74k Ω = (97.74k &lt; -90º)
XC3 = - j97.74 Ω = (97.74 &lt; -90º)


Step 2: Simplify your circuit.


Xeq1 = XR1 + XC1 = 22k - j97.74k = (100.185 &lt; -77.31º)
Xeq2 = (R3*XC1)/(R3+XC1) = 20.94k - 4.713k = (21.46k &lt; -77.31)


Step 2: Solve for Va and Vb.


Va = Vin * (Xeq2/(Xeq1+Xeq2))
Vb = Vin * (R4/(R2+R4))


Step 3: Write an equation for the current load 


ILoad = (Va-Vb) / XLoad


This current is supposed to be going from a to b, but if the sign is negative it means that the current is actually flowing from b to a.

Now this is the current at the frequency you actually gave, now redo steps 1,2, and 3, changing the frequency up 1% and down 1%.