BeerBorg

There's a bit of difference between a good rolling boil and a simmering boil. In my case, it could make up to about 1/2 as much loss with a rolling boil as compared to a simmer.
For being a gallon off, you did pretty well on the OG. Sometimes you have to have a few batches in to see what works for you. Adjust with about 1/2 gallon less and see how that does.

Good point on the boil. My stove, with the 5 gallon pot filled to approximately 3 gallons with LME in it, never gets much above the simmering boil.