I know, you feel regret and regret can be so strong, consuming the entire you. But regret blocks the chance to learn from experience. It is known that teams in the workplace who do not analyze failures repeat them. Those that do, learn. In the workplace, it can be called different names: post mortem, lessons learned, root cause analysis, but the idea is the same. It is very painful but helpful. Otherwise you are flying blind, repeating mistakes.

I still think though that it would be faster with a skilled T who can give you more feedback and new ideas.