Several things come to mind.
The first is that admissions to Stanford, and other similarly highly ranked universities, and admissions to BS/MD programs, is very, very highly competitive and very difficult to predict. You sound like a very strong applicant, and fully academically qualified for Stanford. In an article multiple years ago in the Stanford alumni magazine they said that something like 80% of applicants are fully academically qualified to attend. The acceptance rate is more like 4%.
The second thing that comes to mind is that the best way IMHO to get accepted to a highly ranked university is to be genuine. Do what is right for you. Treat people well. Be a very, very strong student. Participate in whatever ECs, possibly including competitions, that are right for you. If ISEF is right for you, then do it. If something else is right for you, then do something else. This is also my understanding of the “applying sideways” blog on the MIT admissions web site. IMHO this is worth reading if you are applying to any highly selective (aka highly rejective) university:
The third thing that comes to mind is based on your mention of BS/MD programs. I am assuming from this that you would like to become an MD. If you look at the students at highly ranked MD programs, or at pretty much any MD programs, they will have come from huge range of undergraduate universities. You do not need to attend a highly ranked university such as Stanford to get into a highly ranked MD program. If Stanford and other highly ranked universities get slightly more of their students into MD programs, a lot of this, and maybe even all of this, comes from the consistent across-the-board strength of the students who start off at Stanford and similar schools in the first place. There are lots of academically very strong students who attend lower ranked universities, save some $$, do very well, and then go on to very strong graduate programs including very good MD programs (and many other types of graduate programs).
I do not have any doctors in my immediate family. I have however discussed this with a couple of doctors that I know and they both say that the other students in their MD program came from “all over the place”. Other than me the rest of my immediate family either have or are currently getting a biomedical-related graduate degree, and they have all said the same thing.
If you qualify for a LOT of need based financial aid then Stanford and other top schools can be quite affordable. However, if you do not qualify for much or any financial aid these highly ranked private schools can be very expensive.
And 8 years of university are very expensive, and it is typically easier to save on the first 4 years rather than the last 4 years. This all means that you need to budget carefully, and plan for a full 8 years of university.
The vast majority of students who start university thinking “premed” end up doing something else. Keep an open mind. The fact that you already have research experience I think is very good, and is related to one possible form of “something else” that some premed students might eventually settle on as their preferred option.
For applying to universities that would be very good for a premed students, I do not think that you need this. For applying to BS/MD programs, yes I think that this would be helpful. However, most doctors take the more traditional approach of a four year BS, followed by applying to and going to MD or DO programs.
Regarding wet-lab versus computational lab experience, again I think that you should do what is right for you. I see value both ways. Both types of lab experience I think are a good to have, but are things that a student can learn after arriving at university, or after several years of university.
And it sounds like you are doing very well. Good luck with this and best wishes.