What to do if someone is re-uploading my work?

Talk to them and ask them for proper credit. You're not overreacting at all. You spent time and skill making that, and if someone else snaffles it - and sans credit - it's insult and injury.

As to EA having the legal ownership, that's neither here nor there. It isn't the issue at hand. Creatives still deserve credit and common courtesy. You may need to resort to *polite but firm*, but it's all you can really do at the mo.