Doctors don't lie. You'll be fine. That GFR thing can be brought back to normal. Just cut off your protein intake, sodium and potassium rich foods for now.
check this link
https://healthunlocked.com/nkfearlyckd/posts/756806/increasing-gfr-question.

One guy managed to up his GFR from 59 to 100.
Be glad they caught it early.