123, There is no doubt that Helmut Newton seemed a little strange, but his style of photograpy set the stage for what you see today in fashion magazines. If the subject is strong enough and interesting enough all you need to do is light it.
Get your flash off camera. Use a flash bracket. I use the RRS Wedding Pro Flash Bracket.
http://reallyrightstuff.com/flash/04.html. It does a super job, light weight and will put the light where you want it. I have owned every bracket made and this is my favorite. You have to use an L-bracket with it and it's expensive. Check out this bracket review
http://www.aljacobs.com/BEST_WORST2005A.htm.About the diffuser dome. Try some test with and without the dome. The dome reduces the light output. It only softens if there is something to bounce the side light off. The dome does not make the light source larger and larger is what softens the light. It can bounce off a wall or a ceiling and then soften the light by adding another light source, but only if there is a wall or ceiling to bounce off of. Shoot some flash shots with and without the dome and then try to see if or why there is a difference.
I shoot all my weddings with direct flash unless I have a low white ceiling or a close white wall to bounce off of.
My clients like me because I am quick and I get good photographs, and I think they actually like me. I shoot by myself with one assistant to run for me. Flash on camera with flash bracket, seldom do I use a second flash. No light stands, but I do use a tripod to shoot the groups after the wedding.
It's not age that's causing you to lose the dome. Keep it in a case. Same place everytime (I keep the dome in the SB800 case in my camera case). I'm 64 (sounds like a Beatles song)and if I didn't have an organized camera case, I couldn't find anything.
I learned lighting from Dick Balli (Mardick Balli) the guy that invented the umbrella for flash photograhy (yes, he's the one that did it) and he created the Balcar lighting system. He knew more about light than anyone I had ever met. Dick was a fashion photographer and couldn't find what he wanted so he made it. He had a hard time selling lighting in the US because so few photographers understood how it worked. They still don't. Everyone just does what someone else says instead of testing it. I still shoot with Balcar lights and umbrellas.