The high white cell count would indicate an infection being fought somewhere, The urine check did not show any elevated leucocyte count, so it is not in the kidneys.bladder. etc route,
I don't want to worry you but I had a similar episode and went to A&E, It was eventually shown that I had a staph infection in the blood, and this led to my heart attack and a prolonged sojurn in Intensive Care on a strong antibiotic. If you feel wobbly again, call the paramedics asap since delaying it is unwise. It takes a couple of days for the lab to confirm an infection of this type so is not quick. The A&E in my case suspected an infection, and I was placed in isolation in the actual path lab while they did their tests. I am fine now.
I hope your problem is simpler than mine, and that it clears up quickly - there are plenty other bugs in the sea as my mum used to tell me. It does not sound like a diabetes issue especially if only med is Metformin. The symptoms you describe are not normally associated with Metformin and are not DKA either,
The other possibility could be that the white cell count being high is skewing the bgl meter result by making the blood hematocrit ratio out of range that the meter can cope with, and that it is misreading high. Would still be an infection though to do that and it would be quite rare indeed to give false error so great if it had really been a hypo event,
However, the lack of sugar showing in the urine would indicate a low bgl reading, so it could have been a hypo but that again would be a rare event for a Metformin and diet only regime.
So it is a case of wait and see the lab results, unless you go wobbly again.