While all of those symptoms give a pretty clear indication that there is some form of dissociation going on, they do not necessarily mean that a high scorer has DID. The test states that scores above 30 are *associated* with DID... which means that the majority of people with DID have scores above 30, but a score above 30 does necessarily mean that you have it. My understanding is that for DID to be given as a diagnosis someone has to meet the criteria listed in the DSM-IV (sorry, I don't have those criteria handy right now.)
I don't like the DES scale myself, simply because it is so subjective. What do they mean by 'always'? Every single minute of every single day? Once a day? How can anybody accurately quantify an experience on an eleven point scale that goes from 'never' to 'always', and how can anyone ensure that there is consistency in the way that different people rate their experiences? What is 'always' to one may be another persons 'seldom'.
My other gripe with it is exactly what you pointed out - many of the items can be related to other things which have nothing to do with DID at all. For isntance, not being able to hear what is said to you can be caused by an auditory processing disorder and hyperfocus can be related to giftedness or ADHD.

To me it just seems like such a messy test, with too much room for misinterpretation and over and / or under reporting of symptom intensity.
I do think it seems clear that you have some form of dissociative symptoms going on for you, which makes perfect sense given your history of trauma, but I would be really hesitant to say 'yes, you have DID' based on these results. Personally I much favor the DSM as a diagnostic tool.

PS: Sorry this sounds so standoffish.