Really sweet fermenting must

So I started some dandelion wine in the beginning of May. It's been sealed up for approximately 3 months now. I racked it today and racked some into a shot glass to taste how it was getting on.

It is super sweet (as sweet as a finished sweetened wine), though I could also taste that 'alcohol' flavor as well. I'm not sure what would cause my dandelion to be so sweet when it isn't even done fermenting yet. My only guess is that I got a bad pack of yeast or a stuck fermentation.

Any ideas on what could cause this? Should I add more yeast or just let it be for a few more months before tasting again?

Have you taken any gravity readings?

What was teh recipe?

It either stalled or the yeast couldn't handle the alcohol content. What was the OG and what is the gravity now?

"sealed up"

That is probably the issue, yeast needs oxygen to work.

Well by sealed up I mean it's in the fermenter with an airlock, not completely sealed shut.

It is only my third batch and I hadn't really understood how to use my hydrometer at the time that I started it so I don't have gravity readings for it.

The two batches before that didn't have this problem and came out just fine, even though they were essentially amateur hooch.