I'm on Sertraline (though in combination with a long-term mood stabiliser, so not your exact situation).
(Recently, hopefully just for a short while, was upped to 200mg from a long time on 150mg. That dose had suited me and obviously took a fair old time to build up to!)
I do remember feeling Sertraline still wasn't helping at all, in the first 100mg week, up from 50mg.
And then suddenly everything clicked, life gradually felt less overwhelming, and I noticed I was even enjoying what had only a few days before interested me in no way whatsoever.
Small things, but made a massive difference after such a shit low.
As you will know.
On the plus side, compared with the previous SSRI, I find far milder side effects with Sertraline. Have you had any?
Hang on in there. I hope you, too, get an easier time soon.