While it is fun to make wine out of local grapes, Concord grapes will
not make a wine much like what you find in the store. In most cases,
when working with native or cold-hardy grape varieties, you may need
to add sugar. You don't indicate what the starting SG was, or if you
added sugar. Hopefully you are OK on that front.

A TA reading of .973% (or nearly 10g / liter) is fairly high. Some
sugar should help balance the acidity. It probably won't change the
bitterness much. If the bitterness is caused by tannins, there are
things you could do to reduce that (e.g., fining with a little egg
white). If it is caused by other factors, there may not be much you
can do. There isn't a lot you can do if the wine is too thin. Next
time, try not to add much (if any) water. One thing that might help
would be to get some dried elderberries and add them to the wine for a
few weeks. They can add some interesting flavors, which may reduce
the "thin" perception. You could also look at some of the processed
yeast products like Bio-lees or "Sur Lie", as they can add a bit of
body or "mouth-feel".

I think I'd skip the malo-lactic with this batch (I don't think it
would fit well with the Concord flavor profile), just add sulfite and
potassium sorbate to prevent renewed fermentation, then sweeten a bit
to take the edge off the acidity. A small addition of sugar will not
come across as sweet, but will reduce the perceived acidity. Larger
sugar additions will produce a wine that will taste sweet. Do some
"bench trials" -- small samples (maybe a few ounces at a time) with
measured amounts of sugar, to see what effect it has on the wine. You
may find a particular level of sweetness that appeals most to you. Or
you could choose to bottle some with little or no sugar, and some with
more sugar, for different occasions or preferences.

It sounds like a little tweaking should result in a pretty pleasant
wine. Best of luck, and happy fermenting.

Doug