Will my beer be too sweet?

I brewed an Imperial Stout and was looking for 1.120 and got 1.095.  Mash efficiency wasn't that great at 68%.  I used 13 lbs of base grain and the rest was extract.  Even if my yeast ferments the whole way through will my stout taste too sweet?  Mash temp was 158 degrees F.  A little high I know but would this make for too sweet of a stout and if so how would one try to fix this problem to make it drier?
Thanks

My guess is that it will be sweeter than you intended, and you'll drink it anyway.


Live and learn.

I guess I don't want it to be too sweet like a syrup.  Hopefully my hop profile can help balance it out.

The OG of 1.095 vs 1.120 won't make the final beer any sweeter.  Its the final gravity number that would be an indicator of final sweetness.  With that high of an OG it will take a very high attenuating yeast to ferment to a low FG.  The temperature is a little on the high side so there might be more unfermentable sugars that would add to a sweeter taste.

But as Maine said, you made it, you'll like it, you'll drink it and be proud.  It's all good ! ! ! 

Keep a copious amount of notes and take accurate measurements.  Base your next batch on this one fixing one or two things if needed. 

Your fermentation will have a big impact on the final sweetness and body.  The final gravity will be an indicator of the amount of residual sugar and potential sweetness.  Something in the teens could be sweet or not.  In the 20' or higher will probably be sweet.

Several times, my beers with a sweeter perception have finished with a lower gravity than the those which where perceived as less sweet. 

Thinking about it a bit more, residual sweetness can be balanced out by bitterness.
You mentioned 13 lbs of grain with additional extract.  What did you use for hops?

You mashed high and used extract, both of which leave residual sweetness.
However you used hops intended for 25% more initial gravity.

You may end up with more pronounced bitter than sweet.