Current sensor measuring circuit
Although other answers with a current sense IC were downvoted, I'll try with my favorite that I am currently successfully using in a product.  The main difference with the LT6100 is that it has variable gain and 0.5% accuracy.



If you use it with a 100 mΩ resistor, a 2A load with drop 200 mV across the resistor.  Using a gain of 20, this will give a 4v output.  (You can also set the gain to 25, which would be right at the rail of the ADC.)  Note that if you need to measure lower currents with higher accuracy, you can tie the programmable gain pins to the output of the microcontroller.

If you combine the LT6100 with a 100 mΩ 0.5% resistor, you will have 1% accuracy for the combination.

The LT6100 is available from Digi-Key for $2.36.  I don't have any idea what it might cost in your area.