Mulberry Soda gone to Wine?

Hi All,
I made the following brew of mulberry 'soda' but when I taste it is has a strong alcoholic taste to it. This is maybe the second time I have made it.

The recipe and directions I almost followed were this:

3 C Mulberries, destemmed
3 C Water
6 TBSP Sucanat
¼ TSP Bread Yeast

Directions:
Rinse mulberries and press thru a sieve to remove stems. Add mulberries, water and sucanat to a stockpot and simmer for 30 minutes.
Let cool, and then add the yeast.
Use a funnel to pour the soda into bottles.
Leave 1 to 2 inches of empty space at the top of the bottle and attach the bottle caps.
Write the date on the bottles and store them in a warm, draft-free place, ideally at room temperature, for an additional 24 hours. Then refrigerate.
For best results, let the soda sit an additional day or two in the refrigerator before drinking.

Click to expand...

The reason I wrote almost followed is this:
When I checked the bottle after the 24 hours at room temp...it looked like what was originally 1L in volume of soda had reduced a considerable amount...if I had to guess - maybe 10% or so. The bottle also looked stressed (the cap was bulging quite a bit). So, I attempted to let some of the carbonation out, which left a couple of shirts mulberry splattered while the carbonation was slowly 'leaked' by me. There was considerable gas buildup in the bottle.

After letting the cap off, I sampled some, which tasted like mulberries with a bit (or more) of alcohol and yeast.

I stuck the cap back on the bottle, fridged it overnight, and tasted it again just now. Very little carbonation seems to be left and there is still about the same amount of an alcoholic taste.

Any advice or any help is greatly appreciated.

Thanks!

With some pondering, I am thinking I over-shot the yeast and undershot the sugar. Anybody have some input?