Agreed. I started on 50mg and felt worlds better. At 6 months, my doctor thought my PPD should be "cured" and recommended I stop; I tried, but I ended up going back to my family doctor every bit as miserable and out of control as before, so I was back on to 50mg.
I tried cutting my dose at 18 months and at 2 years: both total disasters. At ~3 yrs I tried again because we were TTCing, and I felt the difference but weathered it well. I stayed at 25mg throughout pregnancy and am still there now with my 4mo new baby, doing well but checking in regularly with my doc to go back up if need be since I'm recently post-partum again.
So yeah, I third (fourth?) the recommendation to stick with what works rather than push to reduce or get off the meds. Unlike an aspirin which is a short-term fix, these meds have to heal your brain chemistry and help you rebuild new pathways, so their help really comes long-term. My doc told me from the get-go that there are lots, LOTS of people taking zoloft/sertraline in much higher doses for years and years, so it's earned the nickname "vitamin Z".
Save yourself the trouble and don't make the same mistake I did!