What a thoughtful letter. It sounds to me like you’ve made a great many good efforts. I do understand how hard it is to make friends as an adult. I do understand how it can feel like you are essentially single in a couples world since your partner is happy staying home.
As we get older, many people see themselves as having enough friends and aren’t interested in adding more. Many others have family obligations as well. Everyone has a life. It can seem like no one has the time or interest in making new connections.
Fortunately, there are other people just like you who do want to connect. The challenge is to help you find each other. I don’t think being soft-spoken is the issue. I do think you may be trying too hard too soon.
You need to identify places where you might naturally find other people like yourself. Please find a cause or activity you genuinely care about and genuinely enjoy and do it for its own sake. It could be a book club, a political campaign or a community theater group, for only a few examples. It will get you out of the house and it will let you get to know some people over time. Friendships may unfold naturally. Even if they don’t, you will become a member of a group of people who care about the same thing and who will probably come to care about each other.
I wish you well.