I'm sorry for what you are going through. I suffered with clinical depression for many years, tried 2 medications, did therapy, etc.
I think people's reactions to antidepressants are very individual, both in terms of the chosen med and the dosage. I don't think you can always transfer info from one person to another, so take people's specifics with a grain of salt. So what happens to you on Zoloft might be more similar to what happened to another person on Paxil or Celexa but totally unlike a third person on Zoloft.
I had some PPD but my depression predated that. I did not have any OCD.
The first time I went off, I did it too quickly. It took a while for the symptoms to return, but when they did it was pretty rough. So I went back on and worked with my doctor to change the way I weaned off it. I didn't cut back so much, and when I did, we did a reduced dosage every other day, then every third day, etc. If what you did this time didn't work, you might talk to your doctor about doing that. So, for example, you might do .75 mg 2 days, then .5 the 3rd day, then back to .75 for 2 days, then .5….. After a while (TBD by the doctor and you), you'd cut to alternate days. I'm not telling you exactly what to do - just suggesting a possible middle road between the 2 dosages that you can discuss and brainstorm.
I think it also matters WHY you want to get off, and why you have a particular timetable such as getting down to .25 and off entirely within 6 months. I think you should be flexible about that just in case your body doesn't respond exactly on that schedule. You have multiple issues and a couple of ways in which this imbalance affects you, so your schedule may be different than mine was.
I got some benefit from therapy but that was far from the whole story. I definitely had a chemical imbalance, and while the meds helped a lot with the "lows", they also took away any "highs" so I was tired of feeling "flat". I didn't like the idea of taking meds because they weren't addressing the cause, only the symptom, and they caused some other problems. I changed a lot of things though, including nutrition and exercise. I got SOME benefit from dietary changes, some boost from increased exercise when I had the energy, but I got the most benefit from using some food-based supplements and a lot of help from a network of people who did the same. The support was great. Eventually I reestablished that balance, and in the process I was able to exercise more, which provided other benefits in my mood and energy. But healing and detoxing and getting the balance back after decades of it being out of whack wasn't going to happen overnight. After I got all those ducks in a row, I was able to wean off the medications entirely, and I've been medication-free for a few years. My symptoms have not returned but when I've had a bit of an "off" day, I'm able to address it with my regimen and not with medication.
So definitely use as many avenues of support as you can, and try to be gentle with yourself. If it takes longer than 3 months to get to .25, don't beat yourself up about it. You have to look long term. This is not a recent problem for you, so it's not going to right itself in a short period of time. Try to look at small steps of progress and not be derailed or discouraged if you do it too fast and have to slow up a bit. That doesn't mean you're failing!