I remember my levels suddenly going through the roof and it also coincided with opening a new box of testing strips. I was convinced that there was something wrong with those strips, but within a few days it calmed down again using the same strips. I did go through fluctuations even when not really changing much about my diet.
Morning levels were always the worst and I ended up on insulin for those at around 25 weeks ( was diagnosed at 17wks), but there's nothing you can do diet wise for those levels as it's hormonal.
What you have said sounds fairly normal to me though, and don't forget to take into account those other factors such as sleep and stress that RhiChiChi suggested.