Can someone explain to me how I am contributing to the oppression of women by taking my husband's name upon marriage and using the title 'Mrs', please? (Actions which were taken after considerable thought and discussion between my husband and I - no one forced/expected me to take his name or assumed I would)
Because men don't have to go through it. Men are just Mr. They don't have to decide to use another title (unless it's one to do with profession, like Dr or Prof or Rev.) No one ever questions a man if he says he's Mr Smith. They don't ask him if he's married, or divorced, or what his previous surname was (which he could have; I know one man who changed his surname to his wife's on marriage.) Many people do assume that you will take your husband's name when you get married, that you will be called "Mrs" on marriage, that you have never married if you're "Miss" or that you have been divorced or are lesbian or even feminist (horror!) if you are "Ms". Many webforms will not accept blank for the "Title" field - they force you to make a choice, even when it's entirely unnecessary to whatever service you're signing up for.
Men merely have to identify as male and are automatically assigned all the privileges that our patriarchal society allows them just because they've got a penis. Women have to identify as female, married/unmarried, and whichever choice they make, someone will judge them for it. You'll be judged for being married, you'll be judged for not having married, you'll be judged for being divorced, for changing your name, for not changing your name. Men never have to go through any of this. If there were one single title for women, then women wouldn't have to go through most of this, either. While we insist on using gender-based titles at all, then women will still be judged for being women, but at least we could get away from all the rubbish about whether you're married or not, and people could be more fairly judged for how they actually are, rather than on stereotypes about what single women are like (which also depends on age), what married women are like, what divorced women are like.
Everytime a woman chooses to use Mrs when she gets married, she's helping make sure that all women can be judged on the decisions they make about which title to use, because it means separate titles won't die out and we will all continue to be judged on it. And it doesn't matter whether you're proud of your marriage or never having got married, or whatever else - your opinion doesn't count. It's the rest of society who is judging you and making assumptions about you just because you have chosen Miss, Mrs or Ms. They're judging you, me and every one of us because of it, and my choice is not to be judged until they've more evidence about what I'm actually like to base that judgement on.
No titles is even better, because in the majority of cases, it's not relevant whether I'm single or married or ever have been or ever had a different surname. Institutions and others who actually need to know could just ask that separately - are you male/female/other? (can't remember exactly what forms say these days), are you married, have you ever been married? Have you ever had any other surname? (Because getting married isn't the only reason to have another surname. That is the information they might actually need, not the title, and if they don't need to know that sort of information, they don't need a title at all.