If you are fasting, you shouldn't be taking diabetic medication as that would likely prevent your body from maintaining the necessary glucose level. That is why Dr like to recommend higher carbs intake for those on medication. The risks of losing consciousness or impaired judgement and response at such low glucose level is very real.
Yes please eat some stuff. You can always try fasting again another day.
Well I ate some stuff (bacon, eggs, sausage, tomatoes followed by square of dark chocolate) and went to bed at 4.3! Woke up at 5.0 which is a lot better than previous days after food!
How did you feel at that 2.6? If you felt hypo then don't fast - if you felt okay and have brought your BG back up and still feel okay then, yes, you can fast but be prepared to break it if you need to.
You can hypo on Metformin. I've done it quite spectacularly several times over the years.