Glad to see you are having a happier day with your diabetes!
why is my BG rising when I haven’t eaten anything since my last meal??
Could be many things.
How long since your last meal and what was the meal? Things like pizza need a second dose a couple of hours after my meal.
What were you doing? For instance, I went to he dentist this afternoon, which always raises me because I'm scared. I dosed for this before I went in because I know from experience I will rise, but I didn't dose enough so I still went higher than I like.
A serious workout will raise me as well, I need some insulin for this.
Those three examples are highly personal, you'll need to find out your own patterns. And even then, sometimes diabetes will behave unpredictable.
What long acting insulin are you on and at what time do you take it?
Some long acting insulins tend to 'run out' in the last hours before the next dose.
Otherwise, it could be any of those reasons, plus the colour of your socks: