For someone who has been so recently dx'd, you're doing a damned good job of figuring out how T1 works! You're asking the right questions.
My take on it is this. You took a bolus shot for lunch, lunch was some uncle ben's whole grain, low gi, so your insulin for that probably started kicking in lowering you before the rice started digesting, so you end up low.
So then you, correctly, fire in some glucojuice to bring it back up. I say correctly, because that is correct for a newly dx to do - you're wanting to avoid hypos as much as possible in these first few days, so there's no harm in ending up at 12, even though though you overshot it too much this time - better safe than sorry.
Give it a bit of time, and you'll figure out ways of saying, ok, dropping levels, 15 g glucojuice too much, 4 to 8g glucotabs ok, but don't worry about that too much at the moment.
The end result is that you've got both the rice and the glucojuice kicking in, so 12 isn't a surprise.
You'll learn a lot about T1 by making mistakes and then reviewing them - mistakes aren't a failure: they teach you things.
In this case, you've maybe learned that the shot you took for the amount of carbs in that meal was a little too much, so think about tailing it back a bit for the next same sized meal, or taking the shot nearer to meal time, because the insulin has got to work before the food had turned to glucose. And how, while it is absolutely understandable that you've scoofed a whole glucojuice in response to your first hypo (welcome to the club - hypos ain't nice, don't beat about the bush with them), you've learned that it is possible to overtreat them by taking too much neat glucose. I tend to keep glucojuice for emergencies, your full on hard drop hypos, but for your common or garden slow hypos, a few glucotabs, about 4 to 8g sorts most other hypos out, but you'll learn those subtleties as time goes by, so don't be slow to fill your face with a glucojuice in these early days if you're feeling wobbly even if it puts you too high.
Keep at it, kid, you're doing well!