Hi,
As already recommended:
I'd use one of the 4..20mA measurement circuits.
But if you want to build your own:
I'd use low side sensing
But if you want higb side sensing:
I'd use an unidirectional sensing chip
Your configuration has some drawbacks. This makes it difficult to use your circuit.
*****
One drawback is the 2.5V offset.
Either you live with it (it's the easiest method).
Then just feed the MAX_output to the ADC and subtract the offset from the digital value.
If you want to subtract it on the analog side, then I recommend a difference amplifier. (Opamp circuit)
But it has also drawbacks:
To be able to measure close to zero Amperes you need a rail to rail output opamp.
To be able to measure true zero, then you need a negative supply voltage for the Opamp, (and protection circuit for the ADC)
Klaus