How can I make vanilla fudge that is not too sweet or too soft. I've tried several different recipies, but none are satisfactory.

This might be close to what you are looking for.
https://smittenkitchen.com/2010/03/coconut-milk-fudge/

Since fudge is cooked sugar syrup it's going to be sweet; you could try adding nuts to cut the sweetness, maybe even salted nuts for a salty/sweet thing? The softness is determined by the temperature to which you cook your syrup. If it's too soft, try cooking it a degree or two higher?