I've started a number of things and had trouble finishing. I can relate. My mind just seems to move on once I get what I needed out of it.

No real advice to offer. That would be hypocritical of me. You're not alone.

I will say though that at least this time the French class isn't too hard as it seems you were rocking the material and the content was somewhat easy for you. If you do decide to go you can get an easier win if that makes sense... No judgment, and I support you no matter what you decide. You're fantastic and the starts and stops are just part of your story. They aren't who you are.