1. If your circuit can not drive 200uA loading, then you can try your best to improve the pump power efficency, eg, apply different pump stucture to achieve your target.
2. For power supply range, for enough margin, now the most design have large margin than spec, eg, spec show the chip can work in 1.8 to 2.1v, may be when power is lower down to 1.5v, the chip can work too, Just because, the internal voltage have a constant voltage reference, bandgap outout reference, based on this reference, all internal voltage can be got, so when the input power is changed, can not influence the chip's option.
good luck.
Added after 3 minutes:
By the way, you can caculate the parameters about your pumps, the clk frequency, cap size and , pumps power supply, all of them are determined by your current loading.