I have had a similar experience, however not while pregnant or due to a low blood sugar. I was about 22 and had a bit of a headache during the day, by the evening I had a full right sided weakness as well as a delay in my though process and speech. When someone was speaking to me, it would take me about 5 minutes to work out what they said and then to respond. Luckily, someone realised there was something wrong and I was taken to hospital. From what I can remember, I had some blood tests and was given pethidine for what they diagnosed as a migraine (because of the stroke like symptoms). Very scary at the time not being able to communicate.

In relation to your low blood sugars, your body can have trouble regulating blood sugars when you have a virus, your body uses more energy plus its combined with being pregnant. Temperatures can also effect blood sugars. You ar doing the right things by eating regularly and eating the right things like toast (carbohydrates). Maybe carry some jelly beans around with you.

Hopefully it doesn't happen again and it is just one of those things, scary though!