I don't feel sad exactly but don't really feel anything. Is that depression or am I just going through something?

I don't even know how to explain this properly but I'm going to try. I'm not sad. I don't walk around feeling like everything is terrible. I don't cry or have breakdowns or anything like that. It's more like everything has just gone flat. Things that used to actually make me happy don't really do anything for me anymore. Hanging out with friends feels like something I'm going through the motions of. Music I used to love sounds like background noise. I'll have a perfectly fine day and get to the end of it and realize I didn't actually feel anything the whole time. Not good, not bad, just nothing. And the weird part is that from the outside everything in my life is completely normal. Nothing bad happened. There's no obvious reason for it. Which almost makes it harder to talk about because I don't even know what I'd say. I started thinking about how long this had actually been going on and realized it had been longer than I'd admitted to myself. I'd been brushing it off as being tired or just having an off week for a while now. I also thought about whether what I was feeling was depression or just a phase and whether that distinction even mattered if it was affecting how I was moving through every single day. I thought about why it felt so hard to bring up to anyone when technically nothing was wrong. I realized that waiting for something to actually go wrong before taking it seriously wasn't a good enough reason to keep ignoring it. Feeling nothing for weeks at a time was its own thing worth paying attention to even if I couldn't point to a specific cause. The fact that everything looked fine on the outside didn't mean everything was fine on the inside and I'd been using one to dismiss the other for too long. Talking it through helped me see that I didn't need a label for it to take it seriously. Whether it was depression or something else wasn't the most important question right now. We agreed the best next step was to tell one person in my life what had actually been going on, not the fine version but the real one. I hadn't told anyone because I didn't know how to explain it without sounding dramatic about nothing. But keeping it completely to myself wasn't making it better and I'd been doing that long enough to know that.