Hi Karen,
When working in 3/4, Lilypond is autobeaming 8th notes in groups
of 3 8th notes per pulse (as if it were 6/8) rather than in groups
of 2 8th notes per pulse.
That's not entirely accurate, in 3/4 time the autobeaming by default
creates a single beam for the whole measure. In your example there
were only runs of three quavers at a time which probably gave that
somewhat misleading impression. Putting the following lines after the
time signature might give you the result you expect:
\set Timing.beamExceptions = #'()
\set Timing.baseMoment = #(ly:make-moment 1/4)
\set Timing.beatStructure = #'(1 1 1 1)
Moredetails are at
http://lilypond.org/doc/v2.19/Documentation/notation/beams .