You can buy fast, external ADC modules with built in, selectable gain values. This one works quite well. The maximum gain is 16X, but the six extra bits (over the Uno) should make up the difference for your project.Note that this ADC is absolute, not ratiometric. To mimic a ratiometric ADC you need to use another channel to measure the reference voltage, and calculate the ratio in your code.
the ADC given there won't work as the sample rate is too low, I'm looking for 10kHz.
why does it matter that the ADC is absolute rather than ratiometric?
The answer is simple an operational amplifier.