If you used extract and sugar, then you did NOT miss your O.G. It is impossible to "miss" a predicted OG with extract unless you use the wrong amount of ingredients, or too much water. What happened was that your extract and sugar was not fully mixed with the water in your wort. This is very common, because sugar is much heavier than water, and tends to stay at the bottom of the fermenter. Unless you mixed the wort EXTREMELY well before taking your gravity reading, it is likely that the sample you took from the top of the fermenter did not have the sugar and extract fully mixed in.
By the way, this is pretty normal, and will not affect your beer...
As for the yeast, It should not matter if the smack pack was not mixed/swelled prior to pitching. As long as you used good sanitation, the nutrient in the smack pack will mix in with the wort and yeast, no problem.
My biggest concern with the yeast is that you did not pitch enough. For a 1.080 beer, you really would need 2 of those "smack packs" of yeast, or you would need to grow more yeast in a starter for best results.
Since you are making a Belgian style, the esters from under-pitching the yeast should not be as bad a problem as they could have been. They would be out of place in many other styles, but Belgians are often a little "funky", so it should not seem that unusual in this beer.
