Congrats on 54 days! Hang on to that for dear life. That in and of itself is huge.
I can share my personal experience. I learned early on, childhood, that I had to be happy. And what is happy? Well that was defined by all this external stimulus. I was supposed to be laughing, social, at ease, liked. I was supposed to own a bunch of stuff that my consumer culture told me would make me happy. I was supposed to look good, have money, be successful, be liked. Gee, what could possibly be wrong?
Noone, no thing, no car, no house, no person, no party, no drug, no food can actually make me be ok with me. Its all external and its all temporary. Once the rush wears off I'm still just me, looking at me.
I have learned that contentment is a state of being. Happy? Sad? Those are feelings and they end or change....constantly.
This life thing is an inside job. Doing the right thing daily builds esteem. And it takes time. You've already received practical advice for doing external things to change your mood. That helps. But acceptance that moods just are. Finding contentment comes from within. Life really is made up of a lot of routine. Finding a few things that bring joy is important. But just being, as opposed to doing, is an important skill to master.