Hi Wendy,
Nice work!
Here is a good article about using the TBA120 ICs in NBFM applications:
https://www.g3ynh.info/circuits/TBA120.html
Interesting is your choice of L-C values for the phase-shift network.
According to calculations those values resonate at about 600kHz.
For that inductance to resonate at 455kHz you would need a cap about 815pF.
Is there so much parasitic, internal capacitance there?
Regards, Peter