I concur with the previous two posts. I think you are positioned too far forward on the bike, in a misguided attempt to shorten the reach, putting too much weight on your arms and hands.

As mentioned already, you can always lower and lengthen the stem, but you can't do anything about a frame that doesn't fit as time goes on. Get the bike that fits now. The new 105 is supposed to be as good as the old ultegra, so its nothing to sneez at.