Hi Jade,
If you look at my signature box below, you can read all about reactive hypoglycaemia, which I think the middle link will give you what to look for.
There is always a chance that you have had RH, as I was misdiagnosed.
The only way to find out is by hospital tests.
If you have only a couple of lows that low, I doubt if you have.
You most certainly can have hypos on metformin, that is absolute b.s.!
If you have normal fasting bloods, that is normal for those who have decreased their levels in T2 and RH. Especially after a period of low carbing.
You said you had your low but you ate carbs, I may be wrong but that could have been your body reacting to the change in diet, the stress, the upheaval of being away.
I'm not sure.
You could try doing a glucose test and see what happens after your spike, without eating., but be careful how you do it, it should be done by medical staff supervising.
Just to put your head in total disarray, you can have T2 and RH!
Have a read and ask more questions.
Hope this helps.