Is it possible to increase the current avalible without changing voltage on my DAC circuit?
A good way is the voltage follower circuit. Select an opamp with a low voltage offset, and rail to rail. Make sure the current of the opamp is higher than what the mass flow controller input needs. Vcc is set to near the DAC output (you could go higher if the mass flow controller output will allow. 

Make sure bypass capacitors are used on the Vcc terminals.