Glad you did the tests.
Those (edited to add those
post meal) readings are absolutely and perfectly normal for a non-D. congratulations!
Diabetics tend to run higher than that, but it ain't necessarily a good thing, unless they are avoiding hypos because of medication.
I (as a totally not medically qualified person) am going to stick my neck out and say that on your current diet and exercise regime you need to cut your meds further. Obviously, you need to check that with your medical team!
Don't know anything about diamicron, but I do know that metformin takes a while to build up in the system, and then a while for the levels to drop. So it will take a few days, maybe 2-3 weeks for you to see the benefit of reducing that metformin.
Might be worth you checking how Diamicron works, and if it has a particular time after taking that it hits hardest?
Hope that helps.
Re the dangers of low level bg, I think if you are comfortable and functioning normally, with no hypo symptoms, then I wouldn't worry. Maybe make sure you are not that low when operating machinery or driving though! And check your med levels are right asap.