Nausea on metformin ER?

What do you do if you still have nausea on extended release metformin (Glumetza)? I thought ER was supposed to help. I mean I guess the nausea is slightly better than on standard release but still not good.

I don’t have any side effects if I go down to 1000mg, but I don’t get results until I get up to 1500mg. (I take metformin for PCOS.) Kind of between a rock and a hard place here...