I brewed a St. Paul Porter. I’ve brewed this particular porter many times before. The issue I have with this batch is that due to a number of circumstances (procrastination being one of them), it’s been in the secondary since January. Yes, January. Don’t judge. 
It looks normal. I’ve rocked the carboy occasionally and taken a whiff of the contents - all appears good.
Is there a chance it really is just fine?
Should this affect the amount of priming sugar I use or should I stick with the amount I typically use?
Assuming you are good at sanitation, it is fine. I’d use the same amount of priming sugar but would consider adding a few grains of dried yeast (US-05 would do) to each bottle to ensure that the sugar will be consumed and the beer will properly carbonate.
Whenever I have a doubt about having enough yeast to carb. I use a 1/2 pack of US-04. It gets the job done and leaves a tight little deposit on the bottom of the bottle. Use the same amount of priming sugar as usual
I agree with the others, your beer is just fine but you definitely need to add some more yeast. 1/4 pack should be fine for this purpose (just a sprinkle). Then prime as normal. It might take 3-4 weeks to carbonate, but with fresh yeast, it will eventually carbonate. Without fresh yeast… it is likely to remain flat no matter how much priming sugar you add.
Thanks all. Great advice. Big sigh of relief that my beer’s still good. I’ll go with the additional yeast. Thanks again. Cheers!
