This definitely does not resonate with my experience and what helped me get better. I can tackle big challenges now, but even small failures during severe clinical depression can actually worsen depression.
These are classic symptoms of clinical / major depression. You have not found the right medications that help you yet. Keep seeing a psychiatrist who can help you find the right medication. Each time you switch it can take 10-12 weeks to know if that medication works for you. Please don't give up on the search for medication with a psychiatrist you trust.
If you find your cognitive abilities are lower than they used to be, don't worry. Those will come back too; but are the last thing to return after getting better.