You should read a lot more in the FAQ and posts here. Polyamory is not just about wanting a lot of partners. It's about being completely comfortable with your partner having the freedom to meet, date, and build complete relationships separate from you and without your input or approval.

If that's what you want, and 17F does not want that, then you are incompatible and should break up.

But at 17, with everything you will have the chance to do over the next 5-10 years, do you really need to make any kind of commitment, poly or mono? Wouldn't it be better to date lots of people, while putting your best energies into great friendships, education, and life experience?