“How can I hydrate my eyes without eye drops?”

You can do eye exercises.

At age 15 you are unlikely to have dry eyes.I suspect that the diagnoses is in error. Have your doctor do appropriate tests.

Most dry eye therapy involves the use of eyedrops, both over-the-counter lubricants, and prescription medications that increase tear production. However, I know of a few dry eye therapies that do not involve eyedrops. One is a nasal spray, called Tyrvaya, that stimulates tear release. Omega-3 fatty acids by mouth are known to increase tear production. Plugging or cauterization of the tear drainage ducts allow the tears that your eyes make to stay longer.
Finally, a pellet, called Lacrisert, is placed each morning and has a sustained release of lubricant throughout the day. SO

Drink lots of water and keep fans off

Wash your eyes with warm boiled water