The more time goes on the more convinced I am that the French language does not yield. You can never master it. French will be nobody's mistress. No sir.
Just yesterday in the few little chores I had to do first thing in the morning :
1) I managed to massacre the conjugation of a fairly simple verb. An irregular verb, it's true, but no great shakes. However I messed it up good and proper.
2) I invented a past participle that does not exist. Again a straightforward verb. We are not talking about the subjunctive of paître here. An ordinary, everyday verb.
3) I fouled up a gender, making something masculine instead of feminine. La physique is Physics. Le physique is your physique.
Folks often say I have good French. That's very kind and of course I like it when people say that. It's encouraging.
But of course, the goal is to have an unremarkable French. One where it just doesn't enter people's heads whether your French is good or bad, it is just transparent. It just disappears.
However when people talk of mastering the French language I often say, "Ah non, la langue française ne se maitrise pas, même par les Français. Elle est résistante !" People generally laugh a little ruefully and agree.