trouble amplifying signal from a blood pulse sensor using an LDR
The problem is the high pass filter after the first amplifier. With a 1uF capacitor and a 3.2K resistor the cutoff frequency is about 312 Hz.  Your frequency input is 0.5 Hz to 30Hz and is being attenuated by the filter. At 30 Hz, the gain of the high pass filter is 0.1, so for 20mv in you get 2 mv out. at 3 hz the  gain is 0.01 and at 0.3 Hz the gain is 0.001.

For your circuit, the high pass corner frequency will have to be no more then 0.1 the frequency out from the  sensor