I was depressed from probably age 14 onward. I tried therapy off and on in college, but didn't stick with until around age 22. I had to try 4-5 medications before I found one that worked and had minimal side effects. I saw several FUCKING TERRIBLE therapists/psychiatrists. The fear it wasn't ever going away for good was constant and overwhelming up until maybe a year ago. And if we're being honest, that fear was completely warranted, even if it did impede my progress sometimes. I was never in as much control over my thoughts and emotions as I thought I was back then.
I'm 24 now. My therapist gives me a long list of ways in which my life is better whenever I have doubts. My boyfriend is less specific but says he is definitely seeing improvement. So does my best friend. And recently I've even begun to notice the change in myself.
The way my therapist explains it, the point of therapy isn't to never have a bad thought, it's to make it so that your response to a bad thought is immediate and healtjy, that you don't get trapped in a vicious cycle of feeling like shit and ruminating about it. And medication is to kickstart your brain into being able to think positive when all the neurotransmitters have been fucked up by depression. For me, medication, psychodynamic therapy, and intermittent EMDR when the time is right/when I can afford it has really helped. I actually don't worry about it coming back at all anymore. My therapist has basically said I'm going to kick this thing and be able to move on with my life. And she does this for a living, so I trust her. I'm hoping to be done with meds this year and therapy next year.