I have the same situation as you, my right breast(60-70ml) got only half of that of the left breast(120ml)....
what I did was that I pump the right side for a longer time(5-10mins longer) and empty completely everytime and keep the left one to 10-15 minutes.....slowly in 3-4 days.....two sides almost equal now....only 10-15 ml different
sorry, my PC is not working well and I cannot type Chinese.....
If you all want to increase the supply for the side that it was less, you should pump more and feed more that side, so more stimulation, the more milk can come.