In the last few months, my semen has become very watery.

There is very little smell compared to before. Previously, if I touched it with a finger, the semen would stick and create a string if I pulled the finger away, and now it doesn't. Am I sterile? Am I dying?

Probably not, and no. Semen appearance and texture can change naturally over the course of months, days, or even from one ejaculation to another, due to a variety of factors inculding diet. Read more about semen composition here.