Yeah, you added 1 tsp os acid in addition to 2.5 lbs of cranberries per
gallon? I think your acid level is way high. while yeast can survive
at low pHs, their activity is inhibited. So the fermentation may be
proceeding but it may be imperceptably slow. The cranberries available
in the store are going to be a lot higher in acid than those you pick
fresh too.

To can get calcium carbonate from a wine making store. The carbonate
(which chemically is CO3) will combine with 2 equilivants of acid to
produce a non acidic salt (for cranberry it would be calcium citrate
and calcium malate) and carbon dioxide. If you cannot get that, go to
the grocery store and get some calcium hydroxide, it is sold as
pickling lime. It will produce the same salts plus water. In a pinch
you could add sodium bicarbonate (baking soda), but that will add
sodium to your wine.

there is nothign wrong with fermentin low pH/high acid wines. It is
just that the fermentation tends to be slow and may stick. Even then
in the end you may not be able to drink the resulting wine because of
its acidity. Taste the must now. If it tastes more tart than grape
juice that is an indicator of a high amount of acid (that is no
substitute for a pH meter and a acid test kit).

Anyway, a pinch of carbonate/hydroxide/bicarbonate may be just what
you need. If you take too much acid out you can always add some back
at bottling. just use a tiny bit though, no more than a tsp.