First, never ever ever trust the airlock. It tells you nothing except that the beer might be devolving carbon dioxide. You can only trust your hydrometer to determine the extent of fermentation. Oh, and if you've got lots of icky foam in the fermenter.
That's a good sign.
Second, I suspect you boiled less than the full brew length of five gallons, and probably didn't get the wort mixed sufficiently with the top-off water. Muntons DME produces a consistent 1.045 per pound per gallon. Candisuiker provides a consistent 1.045 per pound per gallon. Honey nets you a consistent 1.035 per pound per gallon. Your recipe, without figuring possible additions of fermentables from the specialty grains, nets you an OG of ~1.070 for 5 gallons. There is no possibility that your gravity could have come out light, unless you forgot to add some of the ingredients, so just relax and rely on my computed OG.
Third, welcome back to the obsessi...er...hobby! Your beer will turn out well.