Like others said, RO should have 95%-99% rejection rate. So if your incoming water is 250 ppm, you should have at worst 12.5 ppm coming out. Then the DI can polish off the rest to 0 ppm. Recommendation is 1 micron sediment filter > 2x 1 micron carbon filter > RO membrane > 2 DI resin.
You probably need to replace your RO filter. And probably change your carbon filters as well.
You can also target your DI to either cation or anion beads based on what your water is high in. My source water is high in silicates. Spectrapure also has a silicabuster DI resin, but it's pretty pricey but I was told it works really well. BRS also has anion or cation only beads to target certain elements.