I read your membrane is a year old, the max is usually 2 years old, some membranes say change after a year. You may well need to change your membrane.

I have an RO at the cottage and this advice is about right; you'll see the TDS going up to unacceptable levels eventually. On the other hand, if the RO is downstream from a softener (ion exchanger), it will likely run for years. I'm still on the original membrane on mine after over five years. The TDS gradually rose from about 12 ppm to 25 over the first couple of years, then stayed put ever since, with minor seasonal variances. I've shut down my bypass loop and simply run straight out of the RO to the machine with no additional chemicals. As a bonus, the water softener also seems to act as a huge prefilter; so I rarely have to change out the filters in the RO. At the cottage, on the other hand, filters all need to be changed several times per year.