Here is what I suggest to improve your chances:
1.Do not waist your time on your Subject test and do not submit your scores. Instead, retake the SAT and try to increase your score to around 1530. You might want to also take the ACT and see what you score. If you get a high score on both exams this will help you a lot more that the SAT Subject. If you don’t do well on the ACT, you will not submit that score.
2.You MUST get a summer internship related to Engineering.
3.Focus your energy and efforts on your essays. You should discuss your leadership, volunteering, your community, and your passions (hobbies). Your stats are important, but mean very little if you don’t covey to the readers that you are good and caring human being. Please understand that the admission officers will be looking at approximately 87,000 applications and they have many students with amazing stats so you want to discuss in your essays what really matters.
4.Ask your English AP teacher and at least one other adult to critic your essays.