Have you tried reading simple texts in French and looking up words you don't understand in the dictionary?
When I'd first moved to France at the age of 7, I couldn't understand a word (duh...) and my dad literally shoved the language into my head by making me read random books and look up words I don't understand from an old, crappy dictionary. Watching French TV helped too. Conversation didn't help so much because I was shy and went to an international school with kids who spoke gibberish. I soon became fluent and my teachers were super impressed and wrote to my parents saying I'm not mentally challenged (I'm not kidding). Learning a new language at such a young age is obviously much easier but I do believe that this method is highly effective.
I'm using the same method (my dad won't help me this time, talk about ditching...) 20 years later with Spanish and it's working - probably because French and Spanish share many similarities. Your background in Latin should be super helpful though, no?
Life with the GMAT:
Jerome: Ben, c'est 20 secondes de plus qu'hier sur le meme parcours! C'etait bien le meme parcours la, non?!
Gigi: Mais t'enerve pas, Jerome, je crois que t'as accroche une porte.