MK: I was brought up with something more (but not exactly) like "bloo-ith-in" with the "oo" and the "i" joined very quickly, but I can't be sure that some people wouldn't say something closer to "bloythin". A soft th sound as in 'breathe', of course. Sometimes, even 15 miles can make a difference to how people pronounce this particular vowel combination. And there's the Wenglish influence.
Once you know about the "dd", as you do, it all suddenly becomes easier, doesn't it!