How well did you really know each other before you got married? Not very well, by the sound of it!!!
You have a young woman who has her own opinions, and they don't automatically accord with yours. She's trying to flex her intellectual muscles as well, and don't be surprised if she sometimes takes the opposing view in a discussion or argument, just because she wants to!!! You men are so predictable, you give your opinion, and even though it sounds fair and reasonable to you, it never occurs to you that we may not share that opinion. Yes, we can argue, as you think "for the sake of it" but maybe it's because we are trying to say " Ok, husband, I have an opinion too. Please shut up and listen to me!"
Personally, I would hate to be looked after by my mother in law, but then, I keep her at arms length from my home. She's a very welcome guest at our house, but she knows not to interfere, or "offer advice" unless asked. There's no way I'd be "looked after" by anyone except my partner, if I was ill.
You need to let your wife make decisions for herself (and sometimes for you too), and discussion means both of you making the decision, not you decide, and she goes with what you wanted anyway.
I don't think you're a bad husband, just one that is still learning that we are much more complicated to understand than you men!!! If you persevere, I think you'll be a very happy couple, just remember, she is your equal in every respect, and deserves to be listened to whenever she has something to say.
By the way, if she's educated, and wants to work, rather than be bored at home, why not support her and encourage her?