If you want to make your piece really Bach-like, you have to be very careful to avoid parallel 5ths and octaves in your counterpoint. Here's a couple of examples that I found:
In bar 2 beat 1 & 2, both parts go up a major 3rd from A to C#
In bar 11 beat 2 and 3, both parts go down from B to A
It's really important to avoid this sort of thing in this style of music because it's all about the independence of lines, and moving consuctively in octaves or fifths (3rds and 6ths are fine, though) weakens this independence.
One more thing - right at the end in bar 25 beat 4 you've got and A in the left resolving to the G# below it, but the right hand already has a G#. This both forces parallel octaves (as the 3rd of the dominant must rise to the tonic) and produces quite a nasty clash!