There's not a set number of times per week, month, or year for couples to have sex. That said, it's basically inevitable that whatever that number is, it's going to decrease over time. I’m not saying sex should (or does) stop being an important part of a relationship! But very few couples continue to have sex like they did when they first got together.
So in your case, I'm not surprised that you've only had sex twice this year. And for at least one of you, that number is totally not OK. Science backs you up there: Studies show that healthy couples (even ones who have been together for many years) have sex about once per week.
Now, I am not one for playing the blame game because relationships are a two-way street. There are certain things both people agree to upon entering a long-term romantic relationship; and that includes meeting the sexual needs of the other person. That's just part of the territory, and when it's not happening I totally get that you're distressed. It’s a shitty situation.
Let's move on to the next point: your wife's anxiety and lack of sex drive. I think it's great that you two went and saw a doctor, but you clearly weren't seeing the right doctor. Sex drive doesn’t just bounce back from zero because you started hitting the gym.
It sounds very much like your wife has female sexual dysfunction (FSD). Basically, FSD is when a woman loses her sex drive and her life is negatively impacted. You can read more about it and find some very valuable resources for treatments here. FSD is incredibly common and it’s a mystery why no one is talking about it. Obviously I'm not a doctor and can't make a diagnosis -- but as your Auntie Gigi, I'd say start there.
Like your wife, I suffer from a serious anxiety disorder. It affects my libido, sexual arousal, and ability to orgasm. And I can say from experience that the fact that your wife's anxiety is affecting your sex life and everyday intimacy is cause for alarm. She needs to find a psychiatrist she trusts and relates to. Try to approach her about this from a place of love, understanding, and wanting to get better. If she’s unwilling to see a mental health specialist, that says a lot about the relationship.
It's critical that your wife stop blaming you for wanting something so basic in a romantic relationship; and instead, starts taking her mental health seriously. I'm certain your wife cares about you. But I'm also afraid she is putting her guilt onto you as a means of escape. She's clearly going through some serious stuff right now. And the best way for you to be a supportive partner is to try to get her the help she needs while acting as supportive as possible.