I know you don't necessarily have to have a message, but I totally get wanting to have a message and not having much drive to write the thing if you don't know what the point is :'D
For me, it's enough just for me to read around; read other people's work (fiction and nonfiction) until I find something to disagree about. I'm a contrarian twit, so it usually doesn't take long So your message can be a 'counter-message' to the message of a work you (at least somewhat) disagree with
Alternately,
It's a starting point! In this case, I suggest reading around about other people's experiences on forums and such; stuff people have talked about directly but you can't find many works of fiction addressing. Hooray for representation XD
If you don't know which other people's experiences to start reading up on, I guess personally I naturally gravitate towards people who ... share my insecurities XD So I guess we're back to square 1 But after going a bit further down the rabbit hole, I do in fact tend to stumble across people whose experiences aren't exactly the same as mine, but just kind of adjacent to mine. Maybe writing about those would be a good idea?