HELP! Trouble going from 3x daily dosing to 2x daily Valium.

I have crossed over to 15 mg of valium from 1.75 mg of ativan, both taken 3x daily.  After the c/o I have stabilized on 5 mg of valium 3x daily for two weeks.  There was some some sedation at first, but it got better during the 2nd week.  This was basically the on s/x I had.

Since valium has such a long half life, this week I tried dosing 7.5 mg valium 2x daily yesterday.  I thought this would simplify things and make my taper easier to manage when I start next week.  The sedation is much worse than it was at dosing 3x daily.  I laid in the recliner all day yesterday and slept for 10 hours last night.  The only reason I woke up this morning was because my alarm went off to remind me it was time to take another dose.

Should I go back to 3x daily or give this a few more days to see if my body gets used to the 2x a day? 

I would appreciate any advice from all of the valium experts out there, or any opinions from anyone.  There has to be someone out there that has had this issue.