Blueberries will have some nutrient effect, but while D47 is a low nutrient yeast, it's still entirely feasible that the sulphurous odour was the lack of nutrient.
The only comment I'd make is that adding it blindly by volume i.e. 1 tsp of xxx etc, is best replaced by getting some druggie scales and weighing it out. As it makes the process more repeatable if you make a mead that turns out to be "the dogs bollocks"!
There are formula's etc for working out the exact requirements, because if it transpired you'd used too much, then it's possible that excess unused/unconsumed nutrients "can", in some cases, cause off flavours etc.
So this isn't a slag off, just trying to explain the benefits of learning about and understanding nutrient additions.
Good on yer for sorting the problem though. I hope your brew turns out a good one.