Is it possible to use my Microsoft account for Java? (Hope this isn't in the wrong category)

The java version is not connected to the windows 10 version (which is the one found in the console and microsoft stores)
So no, you can't use your xbox account on the java edition

Hi, Tyme my name is Oskayra, and will be a pleasure help you

No, you cannot directly transfer your Minecraft Java account to a different Microsoft account. Each Minecraft Java account is associated with a specific Microsoft account, and it's not possible to change this association directly. The only way to play Minecraft Java with a different Microsoft account would be to create a new Minecraft Java account and purchase the game again.

Knowing everything I told you, I'm sorry that you can't change your minecraft account to a different microsoft account, I hope you have a happy day. Oskayra

The only possibility here is that the wrong Microsoft account is signed in on your user which is why the Microsoft balance that is on your Microsoft account isn't showing up.

Hi ghost_hotline

Recently, Microsoft started to integrate Minecraft Java accounts with Microsoft accounts. Could you have merged the wrong account at some point or signed in with the wrong account?

More details on usernames and Gamertags can be found here:

Minecraft: Java Edition Username VS Gamertag FAQ – Home

Check this link for a possible solution:
https://support.xbox.com/en-US/my-account/microsoft-account/something-wrong-microsoft-account