I understand, but I do have a soft spot in my heart for the name Bertha. There was an older lady at my church growing up named Bertha. She was the sweetest lady. If I had a second daughter that might be her middle name, but I would have to find a good first name to go with it.
Gertrude, obviously!
Or Agnes.

I don't like nicknames in general, but I like Gertrude because I like classic names and because it's got a cute nickname imo. Gert, Gertie, those are cute, spunky I think.
Bertha ends up at Bert ....
I know a teenaged Martha; that one I'm not fond of the nickname but like the name itself.