The DR is one of my favorites. I wouldn't consider it a session beer with an OG 1.064 unless three 12 ouncers is the limit for your sessions. I keep the color light and some what reduce perceived body by adding at least half of the LME with 15 minutes left in the boil. The same time I add the Irish moss and yeast nutrient. I don't use a secondary. Confirm FG has been reached around day 14 then dry hop for 7 days. Usually bottle around day 21. By that time the hops have dropped along with any other sediment and excess yeast. I do use a little mesh catch bag at the end of the auto siphon tube to catch stray bits of hops.
Sometimes the dry hop is after 21 days in the primary.
No head on the beer from carbonation may be not enough priming sugar, or more likely not enough warm conditioning time for this moderate gravity beer. I'll condition for 3 to 4 weeks before chilling the first one.
Extra bitterness beyond what the hops provide can come from extracting tannins from the grains. Tannins can be extracted when the pH of the brewing water exceeds 6.0.
What was your timeline for this brew? Have a good picture showing the color in the glass?
A little extra time bottle conditioning may mellow the bitterness if it is the hops that make it seem too bitter. Extra body can come from having less than five gallons in the primary fermentor also.
