This is why it's not a good idea to wait until your senior year in HS is half over before you start preparing for college.
I too wanted to study engineering in college, so I started planning for it between my first and second years in HS. By the time I graduated HS, I had taken 2 classes in algebra, college algebra and trig, calculus, chemistry, and physics.
In the first year in engineering school, I had to take calculus, chemistry, physics, plus a couple of other courses. Because I had already taken the calculus, chemistry, and physics already in HS, it was a much easier transition from the pace of HS to college work. Other classmates in college were not as fortunate, and their first exposure to these subjects was in college, which meant they had to study that much harder and longer to keep up.
The shocker was that the various professors didn't care that you might not have prepared yourself for college work by taking HS classes. The physics professor lectured on the analysis of linear motion, talking about derivatives and integrals, before the math professor had covered these topics in his calculus course. Talk about hitting the ground running!
(The college I went to had a set curriculum, which all students took, and the the school did not excuse you from taking classes even if you had advanced placement. This was why I had prepared by taking some courses in HS).