Have I already ruined my chances?

I am a freshman at a high school in Florida and am trying to get into a strong engineering college, like Carnegie Mellon University, or Stanford.
I am aware of their competitive standards, and this year I am meeting them. I am taking 1 AP, 3 Hon, 1 foreign language, and 2 electives, I have all A’s except for a B in Spanish II, as well as doing Cyber Patriot for an extracurricular. But, I got several B’s in high school-level classes in middle school, causing me to have an unweighed 3.33 GPA. So are my chances blown? Does one year of slip-ups that I didn’t know count bring the whole plan down?

You are a freshman. Relax.

Your plan right now should be to become the best HS student you can be. Put a pin in college- go back to thinking about it a year from now. Make sure you are taking the most challenging math courses your HS offers and make sure you are on track to complete a rigorous bio, chem and physics sequence.

Do not think 'Every point I get off of a homework or test is a point away from going to Harvard."
Think: “I need to do my best, and there will be a college that is right for me when I graduate.”

Do not think “If I don’t go to an Ivy League School/Top20, I am doomed forever.”
Think: “No matter where I go, I can bloom where I am planted. I can get involved and shine.”

Do not think: “My life is over…the kid in my math class is taking 20 APs and I am taking 5. I will never succeed.”
Think: “I need to challenge myself, but only to the point where I can still do well.”

If classes taken during middle school do not appear on the transcript under grades 9-12, not such an issue.

But if you’re aiming high, you need to know it’s more than reciting grades and one EC. Nor is it gpa. Top colleges look at the transcript. And that cores matter more than electives. Make sure you’re looking at what those colleges say, including the recommended course coverage.

Just do the best you can and let the pieces fall where they may. There’s a lot of factors to consider when choosing. Among them are affordability, cultural fit, level of competition for your desired major, etc. You have 2 years before you seriously start looking at colleges. At your age, that’s an eternity. Go do teenager stuff! Just don’t blow anything up, OK?