So sorry to hear you had a bad year with the powdery mildew. Many growers in California were challenged by 2011, as the cooler weather left lots of us battling botrytis, rot and mildew in many areas of the state. I would suggest you go ahead and get your wine in the barrel now, even though it may not be completely through MLF or the MLF hasn’t started to take off yet. You want to make sure your wine is protected from air in the long run, especially if you don’t hear little carbon dioxide bubbles popping up yet. First of all, you should see if your wine is through MLF already. Sometimes that happens with reds, that a native MLF strain will ferment concurrently with the yeast. If you have inoculated for ML and you haven’t had any signs that it’s active (usually you can hear or even taste little bubbles on your tongue within a week or two of inoculating) I would send a sample to your favorite wine lab of choice to get it checked out. I’d hate for you to have a finished ML fermentation and not know about it; that way you’d never get the SO2 in there and in the meantime you might run the risk of a high volatile acidity or other spoilage microbe taking off in the wine. Your alcohol of 14.3% should be no problem for most commercial ML strains available these days. My favorite “bugs” for home winemakers to use are the direct-add strains which are simply freeze-dried ML bacteria that you sprinkle directly into your storage vessel. No culture to build up, no chance of contamination and no questions about whether you added too many or too few.
I certainly wouldn’t filter the wine until you are sure that it has finished the ML fermentation as filtration will remove the very bacteria you need to complete the job (even a loose “bug catcher” filter will remove some of the organisms and the solids that can help support a healthy MLF). Filtration is also just a cosmetic and/or stability step that we usually take right before bottling. Most winemakers won’t filter a wine after MLF, you simply take it to barrel and rack it off any settled solids a couple of months later. Sometimes winemaking is all about stepping away from the barrel, i.e. just letting nature take its course. In this case, what you’re doing is letting gravity do the heavy lifting, or settling, as it were. You’ll be surprised how clear and clarified you can get a wine just by letting gravity take its time in a barrel.