You're liable to get ignored when you come posting on a board saying that you're 17 and know exactly which subspecialty you want to go into because -- well, we've all been 17. Those of us who knew exactly what we wanted to do (I was going to be a theoretical physicist) generally ended up being wrong. We start thinking maybe you're just a troll -- playing with us -- because it's so obvious from this side of the question that you're not quite asking the right questions.
However, having checked your other 4 posts, I've decided that there's a least a small chance you're on the up-and-up, and I'll answer. If you're not, you get a small laugh out of making me say what's already been said hundreds of times on these boards. One feels a little silly sounding like a high-school-commencement speech, but it's tough to avoid in these situations.
I know it's frustrating to be told "you're jumping the gun here" when you talk about your dreams for the future, but... you're jumping the gun here.
Dreaming is good. Envision yourself a surgeon, an immunologist, a mother, a theoretical physicist, a computer programmer, a fighter pilot, and whatever else crosses your mind. Keep your mind open.
This is NOT, however, the time for stressing out about which dream to pick and how to combine them. Dream, but don't worry unless your conclusions will affect your immediate decision-making -- and if you remain interested in medicine, your decision-making for THE NEXT EIGHT YEARS will be exactly the same for any specialty you choose.
Study hard. Play hard. Build and understand your own character and values before you pick a man to marry and spend your life with and have children with. Read widely. Play a sport and an instrument. Don't do any of the dumb things that college kids do (get pregnant by a boyfriend, do drugs, fail out, become alcoholic, marry unwisely) that would derail you from whichever dream it is you end up pursuing.
Start capitalizing "I" and writing in complete (non-run-on) sentences.
About medical school scholarships: they are few and far between. Being a female URM raises your chances slightly, but you still ought to plan for the most likely scenario: that you will have to pay for school like 99.99% of the other medical students in the country.
About combining specialties and children: if you find an easy answer out there, come back and tell us what it is. The only real decision to make now is: don't close off any options now based on hypothetical family situations later. Surgical residencies generally end at (I could be a little off here) 31. More than one 31-year-old out there hasn't even found the father of her children yet, and some (sadly) never will.