I'd put my money on your yeast being alive and well. The best way to know if you've still got lively yeast would be to take a gravity reading. I would give that starter a couple of days, put it in the fridge overnight, decant the liquid, and add another liter or so for another starter. You'll have plenty of yeast by then. Don't rush it, you've procrastinated since spring. What's a few more days?