Hi Cze,
You do not show which type of microphone you will use. An electret mic is common but needs to be powered from a resistor from the positive supply.
Your opamp is not powered and is not biased. Its gain is too low at 3. Its gain should be about 100.
The 555 is oscillating at only 530Hz which is much too low for voices as modulation.
The ground pin of the 555 is not grounded.
Your photo-transistor should have some gain.
The lowpass filter is too simple and will filter out most speech frequencies.
The speaker must be driven from a power amplifier. Try an LM386 little power amplifier.