Sertraline - Been on sertraline for about 11 months now. Started on 25mg now on 100mg

Hi, Tygwyn!
Unfortunately, these medications don't "cure" our disorders... they control them. It's hard to know if it's wise to stop them or not and sometimes the only way to know is to taper off and see how you do.
Some folks have partly situational depression/anxiety but for others it's a clinical situation that may last a lifetime. For the most part studies have shown that the long term use of antidepressants is safe but there have also been reports of some minor effects such as memory impairment (natural aging process?).
Personally, I've been on various antidepressants for over 50 years with no problems at all. I've only had to switch occasionally because sometimes they have a tendency to "poop out" after years of use. When I had to stop them due to an unrelated medical condition my original symptoms returned within weeks.
That isn't to say that the same thing applies to you so work closely with your doctor and if you both agree to try discontinuing the medication do it with a tapering schedule provided by them.
Best regards and I hope all goes well for you in the future.