Trademark Dispute — DMCA takedown on my original content

I publish illustrative scenarios prepared by my practice. All participants and conversations are fictional. The fictional posts are not posts by real users, accounts of client experiences, or reports of actual results.
Illustrative scenario prepared by my practice.
For informational purposes only. This is not legal advice. Laws vary by jurisdiction. Consult a qualified attorney for advice specific to your situation.
Hypothetical question

I've been trying to resolve this on my own but I'm stuck.

DMCA takedown on my original content. I've been dealing with this for about 15 months now and the situation isn't improving.

This involves content I created over the past 22 months. I do not have documentation proving my ownership and timeline.

Do I have a strong case? What should my next steps be?