Hi there! I'm not that knowledgeable about the AP exam structure and how it works, but I'd say that your exam results and academics look great! I applied and was fortunate enough to be admitted to Trinity this year for economics, but I was almost certain that I would be rejected. I'd say that for Cambridge (and top UK universities more generally), it is very important to be academically strong compared with your year group, which you certainly are! Trinity perhaps does attract a higher average scoring candidate than other colleges (especially for engineering, natural sciences, maths etc.) but applying to Trinity overall will not affect your chance of being admitted to Cambridge (due to the pooling system meaning that your chance of being admitted to Cambridge is equal regardless of which college you apply). My advice would be to focus on your AP exams and the ENGAA but don't worry too much about international competitions (UK universities care far less about these than American ones). Instead, make sure you can demonstrate your interest in engineering and make sure your personal statement reflects your passion and interest. Also, make sure you convey this at interview and maybe practice some tricky maths/physics questions to prepare you for this. Based on your results alone, I'd say you definitely have a very good chance of being admitted to Trinity!
About the gap year, I don't think Cambridge minds what you do as long as it is relevant to your course, so it shouldn't be a problem.
Anyway, best of luck with your application!!