My theme is not something my mother wants *RANT/VENT*

Stay strong - I'm having a similar argument with my mom. I'm doing tables that are locations in our favorite fantasy/scifi novels (Gallifrey, Dune, Ankh-Morpork etc). I did relent and won't be doing the "bad side" table (Skaro, Giedi Prime).

Have you seen the fantastic K-9 card box online? It's adorable

I think that wedding sounds... Fantastic! :-) Speaking as someone who's parents are also extremely conservative, just don't talk to them about it. When I got engaged, I told my dad I wanted to get married outside and my uncle to officiate, and he just about had a breakdown, and told me that he didn't want me to have a "hippie wedding". LOL! Well, we found a church that had an outdoor worship area, and we used our pastor, which all ended up better anyhow, and the church was way cheaper and more convenient than even a park, and my uncle died before the ceremony happened. After that I just didn't give my dad any details. If he asked, I would give him vague overviews. Then at the wedding rehearsal he said "What, you are having a unity VOLCANO?". But, when everyone laughed and clapped during that part at the actual ceremony, he calmed down, and when everyone told him what a great time they had, I never heard anything about it being a "hippie weding" again. Honestly, I think he just couldn't imagine it in his head. If you can't avoid talking about details, maybe see if you can make a pinterest with really nice looking, classy doctor who weddings, so she can see more of what you are talking about, and not think it will end up like some crazy circus? I like what you said about giving her little details to work on- keep doing that too; just focus on the non-theme elements with her, and maybe she will forget about them until the wedding. Then, hopefully, when she sees them in action, they won't seem so foreign.

I'm having similar issues with my mother. My fiance and I agreed to a
winter wedding and we're throwing in some Japanese customs (vows are
in Japanese, also including Japanese bamboo flute music to walk down
the aisle, I don't like traditional American wedding march music).
We're not Asian but we're looking to move to Japan permanently in the
coming years. Unfortunately while I'm planning, my mother decided she
wants to wear black to my wedding. Of all things black! I told her
black was not in my color theme and by Japanese custom, her wearing
black is a sign of disapproval of my marriage and an omen for my
marriage to fail. She told me she would "look so good" in
black, a short dress above the knees (keep in mind, she's over 50,
mid-life crisis much!) I've showed her multiple dresses in my color
theme but she's shot them all down in less than five seconds. And she
goes right back to talking about black and even adding in something
sparkle to make it look like a night time snow storm. Just no! She’s
treating my wedding like a hoochie night club get together. At this
point with both our mothers acting like this, I’d be saying “This
is my wedding, my day, not yours. If you can’t fall into the plans
I’ve made and you want to act out, don’t show up.”