OP can I ask why you want to go to groton and Middlesex? I will caution you that barely pulling A’s at your current school may translate into an 85/88 average at groton. Will you be happy with that? The grade deflation and intensity is very real there. On average, at groton, fewer than 10 kids per grade have an average of 93 or over. Will you be happy not being one of those kids?
I don’t think the ssat score is terrible but it doesn’t support an accelerated courses narrative. Accelerated for these schools is kids taking pre calc or calc in 9th grade.
For interviews consider:
Where have you shown academic curiosity outside of the classroom
What do you do to help other people?
Describe a situation where something was difficult and you persevered and overcame.
Can you talk about yourself and your accomplishments while remaining humble?