First of all, I'll just say that I have regrets as well, many regrets. Even though some people look at my scores and think that I had the perfect VCE, it's not like that. I've made decisions which I now look back and think were stupid, but in hindsight, what can I do.
One of the fundamental things you need to understand moving forward is that we all make mistakes in life. This isn't the first time you've made a mistake and it won't be the last. It's OK to make mistakes and it's OK to regret decisions and beat yourself up for it. That's how we learn - we learn by making mistakes and knowing not to make them again. That's why those who get out there and enjoy life and do what they love will always somehow find the right path, because experience is the key to life.
I spent a year of my life doing absolutely nothing, but when I look back, do I think I was stupid? Of course I do! But do I regret it? Of course not, because it was part of a learning experience, I am now surer of what I want to do and even then, at least I had fun throughout the year. At the end of the day, why regret doing something that once made you happy? You can make bad decisions, but you never make decisions which will make you unhappy, cause at the time, they seemed like the right decision.
Deciding to drop Methods may or may not be a stupid decision, not doing well on VCE may or may not be the consequence, it's up to you how you view that. But remember that when you decided to drop Methods, you did it because you believed in it and you thought it was the right thing to do.
Now just stop playing around on ATARCalculator and go have some fun, who cares what happens when results come out, there's always a pathway available for you.