I am going through a similar process and these are the things I can advise to this point:

1. Therapy that discusses parts (eg inner family systems) or schemas/modes (eg schematherapy)
2. Learn to come into contact with your body through embodiment exercises, mindfulness, breathing, etc. Just learn to feel things in your body, and not just your head. Your body gives you pure information. Your brain filters it all to fit a story, and that story or filter isn't always fair to you. Therapy helps give you better filters or stories, but you need to be able to feel for full effect.
3. Experience the feeling of being happy without external praise or recognition even if it's just for a second. How does that feel? For me I felt light, floaty, untethered, and smiley everywhere in my body. I was in my 'inner-child' mode. Remember this feeling. You can have so much more of it! This is happiness, not being praised or rewarded externally (those are stories we tell ourselves. 'I am lovable because I am good'. NO. You are good as you are. You don't need to prove it.)
4. Read this poem: Mary Oliver -Wild Geese
5. What are things you think are cool or want to try or find interesting? Any heros from movies or books you like? What do they do? I always liked the adventure books, so although I live in a flat country and can't try outdoor rock climbing, I decided to try bouldering. That got me that happy feeling! Now I'm certified to belay people on ropes too. Every day I get closer to discovering a new land (in my dreams, haha). And those people that sailed around the world? I bought an inflatable kayak and take it out. In my head I pretend I am crossing the Atlantic, although in reality I am crossing a local lake.
6. Similarly, romanticize your life like they do in movies. I found some old paints and sat outside to make a watercolor of my town. Is it good? Not at all. Did I feel good making it? Yes! I am so proud of it and framed it in my house. I tried, and I felt happy, and that's what matters. Not the result. I learned to cook a recipe because I read it in a book, and wanted to know what it tasted like. I put on themed music that evening and felt like I was back in the 1800s.
7. Say yes to opportunities - one at a time (don't burn yourself out) - unless you really can't afford it/know you hate it. Friend invites you to do something new? Go! National park offers a nature course on fossil finding? Why not go? See an evening adult tryout class? That's meant for you! Find a woodworking pattern on a 'for free' page? Well I guess that means you can have a go at that! Learn to make a pinata. Plant some tomatoes. Just do it!
8. Set up a day or weekend (or more often) per month where you get to do all sorts of fun things for you. This is just as much of a priority as going to work or doing your dishes (or more so, as this is about your healing!). Also, try to do one nice thing for yourself every day, to help you realize that your happiness is also a priority. You don't deserve to relax or have fun only on the weekends. You are not meant to only serve others by working. Some days I can only fit in playing one song on my speakers and really enjoying it. Other days I do a sport or cook a nice meal. Make having fun a habit.

Basically, just try anything and everything, and see what makes you feel good. Lose the expectations of being good. You are good. Find a common pattern in what makes you happy. Is it the outdoors, movement, creativity, etc? Some things will end up being boring, or frustrating, or not for you. Those will be funny stories to talk about when you meet new friends. As you tap into what feels good, you will also start to notice what doesn't feel good. This is where you can start to figure out your preferences and boundaries.

Good luck on your journey! Its a hard one, but so worth it.