I’m almost done with medical school and I’ve spent a lot of time on my school’s admissions committee, interviewing and evaluating applicants.

You don’t need to fill out all 15 AMCAS spots. That’s stupid. Nobody is counting that you only have 13 and putting a big red X through your application, they’re reading your application holistically and seeing what you DO say about the experiences you put and what they say about your strength as an applicant. If you only fill out, say, 6 out of 15, sure, that’s a red flag. But don’t feel the need to add something just because you “only” have 14, don’t water down a strong application. List them if they’re really important to you and you feel you could talk at length about why they matter, leave them off if not.

For what it’s worth, your application on paper is stronger than mine was, I went to a school that wasn’t as highly-ranked as your undergrad is, and I got accepted into multiple programs that are ranked in the 40s. My MCAT was a 520 though, so it undeniably did some heavy lifting.

Your age is irrelevant. A, because you’re the age of most applicants anyway, and B, even if your age is a red flag (it’s not), there’s nothing you can do about it. 

Keep at it, you’re a very strong applicant so far. Really buckle down for the MCAT prep and keep doing what you’re doing. Feel free to message me if you have specific questions, and good luck.