Can I be a UK citizen even though I am over 18?

Hey, my parents received Indefinite leave to remain in the UK after I was born in 1988. According to many websites "If ILR is acquired after the child's birth, the child will not automatically be a British citizen. However the child can be registered as a British citizen under s1(3) of the British Nationality Act 1981 provided application is made before the age of 18." I did not make the application before I was 18, I am 19 years old right now so is it still possible for me to become a UK citizen? How can I go about this as I am a US citizen currently?