What do I fucking write about.

I want to start my own blog and write a long blog posts on here about random ahh thoughts that come in my head every once and then, but I simply can't. I don't know what's stopping me, and I don't know why everything I try to write only has long content about me complaining or venting. I feel like the area for my inspiration for writing is looking like a dry glass of water that hasn't been used for a while. Also I've stopped w my other hobbies such as coding and drawing too lately. It's because of the amount of stress and anxiety I'm feeling about my life and future. My mind is restless and all I think about is music and my future. Lately I've been listening only to rock music and writing poems about my future and stress. I never moved on from my music taste, I mean since I finished high school. I want to be productive and do something useful and find my purpose. Is that a lot I'm asking for?